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{{Short description|Height/width proportion of an image}}
{{About|aspect ratio of still images, films, and digital imagery|display aspect ratio|display aspect ratio|other uses|Aspect ratio (disambiguation)}}

The aspect ratio of an image is the ratio of its width to its height. It is expressed as two numbers separated by a colon, in the format width:height. Common aspect ratios are 1.85:1 and 2.39:1 in cinematography, 4:3 and 16:9 in television, and 3:2 in still photography.
== Some common examples ==
[[File:Aspect Ratio Chart.svg|thumb|Common aspect ratios used in film and display images]]
The common film aspect ratios used in cinemas are 1.85:1 and 2.39:1.<ref name="anamorphic">The 2.39:1 ratio is commonly labeled 2.40:1, e.g., in the [[American Society of Cinematographers]]' ''American Cinematographer Manual'' (Many widescreen films before the 1970 [[Society of Motion Picture and Television Engineers|SMPTE]] revision used 2.35:1).</ref> Two common [[videography|videographic]] aspect ratios are 4:3 (1.{{overline|3}}:1),{{Efn|[[Repeating decimal#Notation|Repeating decimal notation]]}} the universal video format of the 20th century, and [[16:9]] (1.{{overline|7}}:1), universal for [[high-definition television]] and European [[digital television]]. Other cinematic and video aspect ratios exist, but are used infrequently.

In [[still camera]] photography, the most common aspect ratios are 4:3, 3:2 (1.5:1), and more recently found in consumer cameras, 16:9.<ref>{{Cite news|url=http://www.techtree.com/India/News/Panasonic_Introduces_2_New_Cameras/551-97953-893.html |title=Panasonic Introduces 2 New Cameras |publisher=Tech Tree |location=India |url-status=dead |archive-url=https://web.archive.org/web/20090123073441/http://techtree.com/India/News/Panasonic_Introduces_2_New_Cameras/551-97953-893.html |archive-date=2009-01-23 }}</ref> Other aspect ratios, such as 5:3, 5:4, and 1:1 (square format), are used in photography as well, particularly in [[medium format]] and [[large format]].

With television, [[DVD]] and [[Blu-ray]], converting formats of unequal ratios is achieved by enlarging the original image to fill the receiving format's display area and cutting off any excess picture information ([[digital zoom|zooming]] and [[Image cropping|cropping]]), by adding horizontal mattes ([[Letterboxing (filming)|letterboxing]]) or vertical mattes ([[pillarbox]]ing) to retain the original format's aspect ratio, by stretching (hence distorting) the image to fill the receiving format's ratio, or by scaling by different factors in both directions, possibly scaling by a different factor in the center and at the edges (as in ''Wide Zoom mode'').

== Practical limitations ==
In motion picture formats, the physical size of the film area between the [[sprocket]] perforations determines the image's size. The universal standard (established by [[William Kennedy Dickson|William Dickson]] and [[Thomas Edison]] in 1892) is a frame that is four perforations high. The film itself is 35&nbsp;mm wide (1.38&nbsp;in), but the area between the perforations is 24.89&nbsp;mm × 18.67&nbsp;mm (0.980&nbsp;in × 0.735&nbsp;in), leaving the de facto ratio of 1.33:1.<ref name="asc">{{Cite book | last = Burum | first = Stephen | year = 2004 | title = American Cinematographer Manual | edition = 9th | publisher = ASC Press | isbn = 0-935578-24-2 }}</ref>

With a space designated for the standard [[sound-on-film|optical soundtrack]], and the frame size reduced to maintain an image that is wider than tall; this resulted in the [[Academy ratio|Academy]] aperture of 22&nbsp;mm × 16&nbsp;mm (0.866&nbsp;in × 0.630&nbsp;in) or 1.375:1 aspect ratio.

== Cinema terminology ==
The [[motion picture industry]] convention assigns a value of 1 to the image's height; an [[anamorphic]] frame (since 1970, approximately 2.39:1) is often incorrectly described (rounded) as either 2.4:1 or 2.40:1. After 1952, a number of aspect ratios were experimented with for anamorphic productions, including 2.66:1 and 2.55:1.<ref name="arri">{{cite web|date=2011-07-07|title=ALEXA Anamorphic De-squeeze|url=http://www.arri.com/?eID=registration&file_uid=7737|url-status=dead|archive-url=https://web.archive.org/web/20120309120601/http://www.arri.com/?eID=registration&file_uid=7737|archive-date=2012-03-09|access-date=2014-06-21|publisher=Arri}}</ref> A [[Society of Motion Picture and Television Engineers|SMPTE]] specification for anamorphic projection from 1957 (PH22.106-1957) finally standardized the aperture to 2.35:1.<ref name="arri"/> An update in 1970 (PH22.106-1971) changed the aspect ratio to 2.39:1 in order to make splices less noticeable.<ref name="arri"/> This aspect ratio of 2.39:1 was confirmed by the most recent revision from August 1993 (SMPTE 195-1993).<ref name="arri"/>

In American cinemas, the common projection ratios are 1.85:1 and 2.39:1. Some European countries have {{clarify span|1.{{overline|6}}:1|reason=What does the line over the 6 mean?|date=December 2024}} as the widescreen standard. The "Academy ratio" of 1.375:1 was used for all cinema films in the sound era until 1953 (with the release of [[George Stevens|George Stevens']] ''[[Shane (film)|Shane]]'' in 1.{{overline|6}}:1). During that time, television, which had a similar aspect ratio of 1.{{overline|3}}:1, became a perceived threat to movie studios. Hollywood responded by creating a large number of widescreen formats: [[CinemaScope]] (up to 2.{{overline|6}}:1), [[Todd-AO]] (2.20:1), and [[VistaVision]] (up to 2.00:1) to name just a few. The flat 1.85:1 aspect ratio was introduced in May 1953, and became one of the most common cinema projection standards in the United States and elsewhere.

The goal of these various lenses and aspect ratios was to capture as much of the frame as possible, onto as large an area of the film as possible, in order to fully utilize the film being used. Some of the aspect ratios were chosen to utilize smaller film sizes in order to save film costs while other aspect ratios were chosen to use larger film sizes in order to produce a wider higher resolution image. In either case the image was squeezed horizontally to fit the film's frame size and avoid any unused film area.<ref>{{cite journal|url=http://www.filmanddigitaltimes.com/wp-content/uploads/2013/08/Anamorphic-Math-FDTimes.pdf |title=Anamorphic Now |access-date=2014-06-21 |pages=24–31 |issue=53 |journal=Film and Digital Times |date=April 2013}}</ref>

=== Movie camera systems ===
The development of various film camera systems must ultimately cater to the placement of the frame in relation to the lateral constraints of the perforations and the optical soundtrack area. One clever wide screen alternative, [[VistaVision]], used standard 35&nbsp;mm film running sideways through the camera gate, so that the sprocket holes were above and below frame, allowing a larger horizontal negative size per frame as only the vertical size was now restricted by the perforations. There were even a limited number of projectors constructed to also run the print-film horizontally. Generally, however, the 1.50:1 ratio of the initial VistaVision image was optically converted to a vertical print (on standard four-perforation [[35 mm movie film]]) to show with the standard projectors available at theaters, and was then masked in the projector to the United States standard of 1.85:1. The format was briefly revived by [[Lucasfilm]] in the late 1970s for special effects work that required a larger negative size (due to image degradation from the optical printing steps necessary to make multi-layer composites). It went into obsolescence largely due to better cameras, lenses, and film stocks available for standard four-perforation formats, in addition to increased lab costs for making prints in comparison to more standard vertical processes. (The horizontal process was also adapted to 70&nbsp;mm film by [[IMAX]], which was first shown at the Osaka '70 Worlds Fair.)

[[16 mm film#Super 16 mm|Super 16&nbsp;mm film]] was frequently used for television production due to its lower cost, lack of need for soundtrack space on the film itself (as it is not projected but rather transferred to video), and aspect ratio similar to 16:9 (the native ratio of Super 16&nbsp;mm is 15:9). It also can be blown up to 35&nbsp;mm for theatrical release and therefore is sometimes used for feature films.

== Current video standards ==

=== 1:1 ===
Square displays are rarely used in devices<ref>{{Cite web|url=https://www.gsmarena.com/blackberry_passport-6457.php|title=BlackBerry Passport – Full phone specifications|website=www.gsmarena.com|language=en-US|access-date=2018-11-29}}</ref><ref>{{Cite web|url=https://www.gsmarena.com/sony_smartwatch_3_swr50-7691.php|title=Sony SmartWatch 3 SWR50 – Full phone specifications|website=www.gsmarena.com|access-date=2019-01-24}}</ref> and monitors.<ref>{{Cite news|url=https://www.geek.com/news/eizos-27-inch-3k-display-is-perfectly-square-1610009/|title=Eizo's 27-inch 3K display is perfectly square - Geek.com|date=2014-11-20|work=Geek.com|access-date=2018-11-29|language=en-US|archive-date=2018-11-30|archive-url=https://web.archive.org/web/20181130003730/https://www.geek.com/news/eizos-27-inch-3k-display-is-perfectly-square-1610009/|url-status=dead}}</ref> Nonetheless, video consumption on social apps has grown rapidly and led to the emergence of new video formats more suited to mobile devices that can be held in horizontal and vertical orientations. In that sense, square video was popularized by mobile apps such as [[Instagram]] and [[Vine (service)|Vine]] and has since been supported by other major social platforms including [[Facebook]] and [[Twitter|X]]. It can fill nearly twice as much screen space compared to 16:9 format (when the device is held differently while viewing from how video was recorded).

=== 4:3 ===
{{main|Fullscreen (aspect ratio)}}

4:3 (1.33:1) (generally read as Four-Three, Four-by-Three, or Four-to-Three) for standard television for fullscreen aspect ratio 1.33:1 has been in use since the invention of [[movie camera|moving picture cameras]], and many [[computer monitor]]s used to employ the same aspect ratio. 4:3 was the aspect ratio used for [[35 mm movie film|35&nbsp;mm films]] in the [[silent film|silent era]]. It is also very close to the 1.375:1 [[Academy ratio]], defined by the [[Academy of Motion Picture Arts and Sciences]] as a standard after the advent of optical [[sound-on-film]]. By having TV match this aspect ratio, movies originally photographed on 35&nbsp;mm film could be satisfactorily viewed on TV in the early days of the medium (i.e. the 1940s and the 1950s).

With the adoption of [[high-definition television]], the majority of modern televisions are now produced with 16:9 displays instead. Apple's [[iPad]] series of [[tablet computer|tablets]] continue to use 4:3 displays (despite other Apple products typically using widescreen aspect ratios) to better suit use as an [[e-reader]]; however, the 2018 iPad Pro 11-inch uses a 1.43:1 aspect ratio.<ref>{{Cite web|url=https://www.macworld.com/article/1146035/ipad-screen.html|title=Why Apple chose the iPad's screen format|last=McElhearn|first=Kirk|date=2010-02-01|website=Macworld|language=en|access-date=2019-07-24}}</ref>

=== 14:9 ===
{{main|14:9 aspect ratio}}
14:9 (generally named as Fourteen-by-Nine, Fourteen-Nine, and Fourteen-to-Nine) is the aspect ratio mainly used when the 4:3 programs are cropped.<ref name=":0">{{Cite book |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1379-0-199811-S!!PDF-E.pdf |title=BT.1379 - Framing of wide-screen 16:9 and standard 4:3 aspect ratio productions to achieve a common production format during a transition period to wide-screen 16:9 production and broadcasting |publisher=ITU Radiocommunication Assembly |year=1998}}</ref><ref name=":1">{{Cite book |url=https://tech.ebu.ch/docs/r/r093.pdf |title=R93-1998 - Compromise Scanned Area Dimensions for Television from 35 mm Wide-Screen Films |publisher=EBU |year=1998}}</ref>

=== 16:10 ===
{{Main|16:10 aspect ratio}}
[[16:10 aspect ratio|16:10]] (8:5) is an [[Display aspect ratio|aspect ratio]] mostly used for [[computer display]]s and [[tablet computer]]s. The width of the display is 1.6 times its height. This ratio is close to the [[golden ratio]] "<math>\varphi</math>" which is approximately 1.618. LCD computer displays using the 16:10 ratio started to appear in the mass market from 2003. By 2008, 16:10 had become the most common aspect ratio for [[LCD monitor]]s and [[laptop]] displays.<ref>{{cite web |url=http://lowendmac.com/musings/08mm/10-percent-notebook.html |title=With 10% of the U.S. Notebook Market, Where Will Apple Go Next? |last=Knight |first=Dan |date=2008-09-19 }}</ref> Since 2010, however, 16:9 has become the mainstream standard, driven by the 1080p standard for high definition television and lower manufacturing costs.<ref name="displaysearch">{{cite web |url=http://www.displaysearch.com/cps/rde/xchg/SID-0A424DE8-28DF6E59/displaysearch/hs.xsl/070108_16by9_PR.asp |title=Product Planners and Marketers Must Act Before 16:9 Panels Replace Mainstream 16:10 Notebook PC and Monitor LCD Panels, New DisplaySearch Topical Report Advises |publisher=DisplaySearch |date=2008-07-01 |access-date=2011-09-08 }}</ref><ref name="engadget">{{cite web |url=https://www.engadget.com/2008/07/02/widescreen-lcds-going-widescreen-by-2010 |title=Widescreen LCDs going widescreen by 2010 |publisher=Engadget |last=Ricker |first=Thomas |date=2008-07-02 }}</ref>

In 2005–2008, 16:10 (1.6:1) overtook 4:3 as the most sold aspect ratio for LCD monitors. At the time, 16:10 also had 90% of the notebook market and was the most commonly used aspect ratio for laptops.<ref name="displaysearch"/> However, 16:10 had a short reign as the most common aspect ratio. Around 2008–2010, there was a rapid shift by computer display manufacturers to the 16:9 aspect ratio and by 2011 16:10 had almost disappeared from new mass market products. According to [[Net Applications]], by October 2012 the market share of 16:10 displays had dropped to less than 23 percent.<ref>{{cite web |url=http://marketshare.hitslink.com/report.aspx?qprid=17&qpsp=165&qpnp=1&qptimeframe=M |title=Screen Resolutions |publisher=Net Applications |date=October 2012 |access-date=2013-04-20 }}</ref>

Notably, Apple used 16:10 for all of its [[MacBook]] models until 2021, when the [[MacBook Pro#Fifth generation (Thick Unibody)|5th-generation MacBook Pro]] switched to a taller aspect ratio of approximately 1.54:1.<ref>{{Cite web|date=2021-10-18|title=MacBook Pro 16 vs. MacBook Pro 14: All the Differences|url=https://www.digitaltrends.com/computing/macbook-pro-16-inch-vs-macbook-pro-14-inch/|access-date=2021-11-27|website=Digital Trends|language=en}}</ref> The [[MacBook Air]] continues to use 16:10 as of 2022.<ref>{{cite web|author=Apple|title=MacBook Air - Technical Specifications|url=https://www.apple.com/macbook-air/specs/|access-date=2022-01-07}}</ref>

===16:9===
{{Main|16:9 aspect ratio}}
[[16:9 aspect ratio|16:9]] (1.77:1) (generally named as Sixteen-by-Nine, Sixteen-Nine, and Sixteen-to-Nine) is the international standard format of [[High-definition television|HDTV]], non-HD digital [[television]] and analog widescreen television [[PALplus]]. Japan's [[Multiple sub-Nyquist sampling encoding|Hi-Vision]] originally started with a 5:3 (= 15:9) ratio but converted when the international standards group introduced a wider ratio of {{frac|5|1|3}} to 3 (= 16:9). Many [[digital video]] cameras have the capability to record in 16:9 (= 4<sup>2</sup>:3<sup>2</sup>), and 16:9 is the only widescreen aspect ratio natively supported by the [[DVD-Video#Video data|DVD]] standard. DVD producers can also choose to show even wider ratios such as 1.66:1, 1.75:1, 1.77:1 and 1.78:1<ref name="anamorphic" /> within the 16:9 DVD frame by [[hard matting]] or adding black bars within the image itself. The 16:9 aspect ratio was used often in British TVs in the United Kingdom in the 1990s, and is also used in smartphones, laptops, and desktops.

=== 1.85:1 ===
Equivalent to integer ratio of 37:20. When [[movie theater|cinema]] attendance dropped, Hollywood created [[widescreen]] aspect ratios in order to differentiate the film industry from TV, with one of the most common being the 1.85:1 ratio.<ref>{{Cite book|url=https://books.google.com/books?id=1DFEDwAAQBAJ&pg=PA31|title=Civil Servants on the Silver Screen: Hollywood's Depiction of Government and Bureaucrats|last=Pautz|first=Michelle C.|date=2017-12-29|publisher=Lexington Books|isbn=978-1-4985-3913-5|pages=31|language=en}}</ref><ref>{{Cite web|url=https://www.widescreen.org/aspect_ratios.shtml|title=Aspect Ratios and Camera Formats|author=Berger, John L.|year=2019|website=www.widescreen.org|access-date=2018-10-30}}</ref>

=== 2.00:1===
{{Main|Univisium}}
The 2.00:1 aspect ratio was first used in the 1950s for the RKO Superscope format.<ref>{{Cite web|url=http://www.widescreenmuseum.com/widescreen/wingss1.htm|title=Widescreen Museum – CinemaScope Derivatives – Superscope 1|website=www.widescreenmuseum.com|access-date=2018-11-02}}</ref><ref>{{Cite web|url=http://vashivisuals.com/the-hot-new-filmmaking-aspect-ratio/|title=The Aspect Ratio of 2.00 : 1 is Everywhere {{!}} VashiVisuals|website=vashivisuals.com|language=en-US|access-date=2018-11-02}}</ref>

Since 1998, cinematographer [[Vittorio Storaro]] has advocated for a format named "[[Univisium]]" that uses a 2.00:1 format.<ref>{{cite web|url=http://vittoriostoraro-asc.blogspot.com/2007/03/what-is-univisium.html|title=. . : : VITTORIO STORARO : : . .: What is UNIVISIUM?|last=Eelvee|date=4 March 2007}}</ref> Univisium has gained little traction in the theatrical film market, but has recently been used by [[Netflix]] and [[Amazon Video]] for productions such as ''[[House of Cards (American TV series)|House of Cards]]'' and ''[[Transparent (TV series)|Transparent]]'', respectively. This aspect ratio is similar to the 1.90:1 standard acquisition formats mandated by these content platforms and is not necessarily a creative choice.<ref>{{Cite news|url=http://www.indiewire.com/2017/04/netflix-amazon-4k-documentary-1201799403/|title=What Amazon and Netflix's Demand for 4K Means for Documentaries|last=O'Falt|first=Chris|date=2017-04-04|work=IndieWire|access-date=2018-05-10|language=en-US}}</ref>

Moreover, some mobile devices, such as the [[LG G6]], [[LG V30]], [[Huawei Mate 10 Pro]], [[Pixel 2|Google Pixel 2 XL]], [[Oneplus 5T|OnePlus 5T]] and [[Sony Xperia XZ3]], are embracing the 2.00:1 format (advertised as 18:9), as well as the [[Samsung Galaxy S8]], [[Samsung Galaxy Note 8]], [[Samsung Galaxy S9]] and [[Samsung Galaxy Note 9]] with a slightly similar 18.5:9 format.<ref>{{cite web|url=https://www.phonearena.com/news/So-what-is-this-21-Univisium-display-ratio-on-the-LG-G6_id90593|title=So, what is this 2:1 Univisium display ratio on the LG G6 and likely the S8?|first=Daniel|last=Petrov|website=Phone Arena|date=28 February 2017 }}</ref><ref>[https://www.hihonor.com/global/products/smartphone/honor7x/ The official Honor website] {{Webarchive|url=https://web.archive.org/web/20181203074439/https://www.hihonor.com/global/products/smartphone/honor7x/ |date=2018-12-03 }} displays that it has an 18:9 ratio (visit the gaming tab).</ref> The Apple [[iPhone X]] also has a similar screen ratio of 19.5:9 (2.16:1).

=== 2.39:1 ===
{{Main|Anamorphic format|Anamorphic widescreen}}

Anamorphic format is the [[cinematography]] technique of shooting a [[widescreen]] picture on standard [[35mm movie film|35 mm film]] or other visual recording media with a non-widescreen native aspect ratio. When projected the image is then stretched back into the original proportions.

== Obtaining height, width, and area of the screen ==
Often, screen specifications are given by their diagonal length. The following formulae can be used to find the height (''h''), width (''w'') and area (''A''), where ''r'' stands for ratio, written as a fraction of ''x'' by ''y'', and ''d'' for diagonal length.

:<math>r = \frac{x}{y}</math>
:<math>h = \frac{d}{\sqrt{r^2+1}} = \frac{y \times d}{\sqrt{x^2+y^2}}</math>
:<math>w = \frac{r\times d}{\sqrt{{r^2}+1}} = \frac{x \times d}{\sqrt{x^2+y^2}}</math>
:<math>A = \frac{r\times d^2}{{r^2}+1} \quad= \frac{x \times y \times d^2}{x^2+y^2}</math>

== Distinctions ==
{{multiple issues|section=yes|
{{Unreferenced section|date=March 2023}}
{{cleanup|1=section|reason=content overlaps with section [[Pixel aspect ratio#Introduction]]|date=May 2023}}
}}
This article primarily addresses the aspect ratio of images ''as displayed,'' which is more formally referred to as the '''[[display aspect ratio]] (DAR)'''. In [[digital image]]s, there is a distinction with the '''{{visible anchor|storage aspect ratio}} (SAR)''', which is the ratio of [[Display resolution|numbers of pixels]]. If an image is displayed with [[square pixel]]s, then these ratios agree. If, instead, non-square ("rectangular") pixels are used, then these ratios differ. The aspect ratio of the pixels themselves is known as the '''[[pixel aspect ratio]] (PAR)''' – for square pixels this is 1:1 – and these are related by the identity:
:{|class="wikitable"
|SAR&nbsp;×&nbsp;PAR&nbsp;=&nbsp;DAR
|}
Rearranging (solving for PAR) yields:
:{|class="wikitable"
|PAR&nbsp;=&nbsp;DAR/SAR
|}
'''For example:'''
* A 640&nbsp;×&nbsp;480 [[VGA]] image has
** a SAR of 640/480 = 4:3
** and if displayed on a 4:3 display (DAR = 4:3), has square pixels, hence a PAR of 1:1.
* By contrast, a 720&nbsp;×&nbsp;576 [[D-1 (Sony)|D-1]] PAL image has
** a SAR of 720/576 = 5:4
** but is displayed on a 4:3 display (DAR = 4:3), so by this formula it would have a PAR of (4:3)/(5:4) = 16:15.

However, because standard definition digital video was originally based on digitally sampling analog television, the 720 horizontal pixels actually capture a slightly wider image to avoid loss of the original analog picture. In actual images, these extra pixels are often partly or entirely black, as only the center 704 horizontal pixels carry actual 4:3 or 16:9 image. Hence, the actual pixel aspect ratio PAR for PAL video is a little different from that given by the formula, specifically 12:11 for PAL and 10:11 for NTSC. For consistency, the same effective pixel aspect ratios are used even for standard definition digital video originated in digital form rather than converted from analog. For more details refer to the [[Pixel aspect ratio#Analog-to-digital conversion|main article]].

In analog images such as film there is no notion of pixel, nor notion of SAR or PAR, and "aspect ratio" refers unambiguously to DAR. Actual displays do not generally have non-square pixels, though digital sensors might; they are rather a mathematical abstraction used in resampling images to convert between resolutions.

Non-square pixels arise often in early digital TV standards, related to digitalization of analog TV signals – whose horizontal and vertical resolutions differ and are thus best described by non-square pixels – and also in some digital videocameras and computer [[display mode]]s, such as [[Color Graphics Adapter]] (CGA). Today they arise particularly in [[transcoding]] between resolutions with different SARs.

DAR is also known as ''image aspect ratio'' and ''picture aspect ratio'', though the latter can be confused with ''pixel'' aspect ratio; PAR is also known as ''sample aspect ratio'', though it can also be confused with ''storage'' aspect ratio.

== Previous and currently used aspect ratios ==
{{for|a listing of computer resolutions and aspect ratios|list of common resolutions}}
{{for|a full listing of film formats, including their aspect ratios|list of motion picture film formats}}
[[File:Filmaspectratios.svg|thumb|upright=1.3|Comparison of several film aspect ratios with the heights forced to be equal images]]

; '''1:2.32'''
: The first [[television]] aspect ratio, used by [[John Logie Baird]]'s 30-line mechanical television in the early 1930s.<ref>{{Cite web|url=http://www.imdb.com/title/tt0360777/reference/|title=The Man with a Flower in His Mouth (TV Movie 1930) - IMDb|via=www.imdb.com}}</ref>
; '''1.19:1''' ~ '''19:16'''
: Sometimes referred to as the [[Movietone sound system|Movietone]] ratio, this ratio was used briefly during the transitional period when the film industry was converting to sound, from 1926 to 1932 approx. It is produced by superimposing an optical soundtrack over a full-gate 1.{{overline|3}} aperture in printing, resulting in an almost square image. Films shot in this ratio are often projected or transferred to video incorrectly using a 1.375:1 mask or squashed to 1.375:1. Examples of films shot in the Movietone ratio include ''[[Sunrise: A Song of Two Humans]]'', ''[[M (1931 film)|M]]'', ''[[Hallelujah! (1929 film)|Hallelujah!]]'', and, significantly more recently, ''[[The Lighthouse (2019 film)|The Lighthouse]]''.<ref>Scott Eyman, ''The Speed of Sound: Hollywood and the Talkie Revolution, 1926–1930'', New York, Simon & Schuster (1997), p. 222.</ref><ref>{{Cite web|url=https://www.hollywoodreporter.com/heat-vision/lighthouse-explained-how-it-connects-witch-1250507|title='The Lighthouse,' 'The Witch' and the Horror of Robert Eggers|website=The Hollywood Reporter|date=29 October 2019|language=en|access-date=2019-11-10}}</ref> A trend arising from the widespread use of smartphones is [[vertical video]] that is intended for viewing in [[Page orientation|portrait mode]]. The format was popularized in particular by apps such as [[Snapchat]], [[Instagram]], and [[YouTube]]—which all offer means for publishing vertical videos as content and [[Video advertising|advertising]].<ref name="Fratti">{{cite news |author=Fratti, Karen |date=20 October 2015 |title=Grabyo Adds Square, Vertical Video Capabilities |publisher=Ad Week |url=http://www.adweek.com/lostremote/grabyo-adds-square-vertical-video-capabilities/54238 |access-date=24 July 2016}}</ref><ref>{{cite web |author=Lim, Shawn |date=27 September 2018 |title='Nobody will ask why they need vertical videos now': Snap on why it welcomes competition from rivals |url=https://www.thedrum.com/news/2018/09/27/nobody-will-ask-why-they-need-vertical-videos-now-snap-why-it-welcomes-competition |access-date=28 September 2018 |work=The Drum}}</ref><ref>{{Cite news |last=Alcántara |first=Ann-Marie |date=2022-08-08 |title=Marketers Test YouTube Shorts, One More Rival to TikTok |language=en-US |work=[[The Wall Street Journal]] |url=https://www.wsj.com/articles/marketers-test-youtube-shorts-one-more-rival-to-tiktok-11659983896 |access-date=2023-02-01 |issn=0099-9660}}</ref>
; '''1.25:1''' = '''5:4'''
: The once-popular aspect for larger format computer monitors, especially in the guise of mass-produced 17" and 19" LCD panels or 19" and 21" CRTs, using 1280×1024 (SXGA) or similar resolutions. Notably one of the few popular display aspect ratios narrower than 4:3, and one popularised by business (CAD, DTP) rather than entertainment use, as it is well-suited to full-page layout editing. Historically, 5:4 was also the original aspect ratio of early 405-line television broadcasts, which progressed to a wider 4:3 as the idea of broadcasting cinema films gained traction.
; '''1.{{overline|3}}:1''' = '''4:3''' = '''12:9'''
: 35&nbsp;mm original silent film ratio, today commonly known in TV and [[video]] as 1.33:1. Also standard ratio for [[MPEG-2]] video compression. This format is still used in many personal video cameras today and has influenced the selection or design of other aspect ratios. It is the standard [[Super 35]] mm ratio.
; '''1.37:1''' ~ '''48:35'''
: 16&nbsp;mm and 35&nbsp;mm standard ratio.
; '''1.375:1''' = '''11:8'''
: 35&nbsp;mm full-screen sound film image, nearly universal in films between 1932 and 1953. Officially adopted as the [[Academy ratio]] in 1932 by [[Academy of Motion Picture Arts and Sciences|AMPAS]]. Rarely used in theatrical context nowadays, but occasionally used in other contexts.
; '''1.43:1'''
: [[IMAX]] format. IMAX productions use 70&nbsp;mm wide film (the same as used for 70&nbsp;mm feature films), but the film runs through the camera and projector horizontally. This allows for a physically larger area for each image.
; '''1.5:1''' = '''3:2'''
: The aspect ratio of 35&nbsp;mm film used for still photography when eight perforations are exposed. Also the native aspect ratio of [[VistaVision]], for which the film runs horizontally. Used on the [[ChromeOS]]-based [[Chromebook Pixel]] notebook PC, the [[Game Boy Advance]] portable game console, mostly all [[Microsoft Surface]] [[2-in-1 laptop]]s  and [[Surface Studio]].
; '''1.{{overline|5}}:1''' = '''[[14:9 aspect ratio|14:9]]'''
: Widescreen aspect ratio sometimes used in shooting commercials etc. as a compromise format between 4:3 and 16:9. When converted to a 16:9 frame, there is slight [[pillarbox]]ing, while conversion to 4:3 creates slight [[letterboxing (filming)|letterboxing]]. All widescreen content on [[Freeform (TV channel)|ABC Family]]'s SD feed until January 2016 was presented in this ratio.
; '''1.6:1''' = '''[[16:10]]''' = '''8:5'''
: Widescreen computer monitor ratio (for instance, 1920×1200 resolution).
; '''1.66:1''' or '''1.{{overline|6}}:1''' = '''5:3''' = '''15:9'''
: Early 35&nbsp;mm widescreen ratio, originally invented by [[Paramount Pictures]], later a standard among several European countries.{{Which|date=November 2018}} It is also the native Super 16&nbsp;mm frame ratio. Sometimes this ratio is rounded to 1.67:1. From the late 1980s to the early 2000s, [[Walt Disney Animation Studios|Walt Disney Feature Animation]]'s [[Computer Animation Production System|CAPS program]] animated their features in the 1.{{overline|6}}:1 ratio (a compromise between the 1.85:1 theatrical ratio and the 1.33:1 ratio used for home video); this format is also used by the [[Nintendo 3DS]]'s top screen.
; '''1.75:1''' = '''7:4'''
: 35&nbsp;mm widescreen aspect ratio used by The Metro Goldwyn Mayer Company and The Warner Brothers Company from 1953 to 1955 and since abandoned and The Walt Disney Company has cropped the old classic post-1950s 1.33:1 fullscreen films to the 1.75:1 widescreen aspect ratio of their DVDs including ''[[The Jungle Book (1967 film)|The Jungle Book]]''.
; '''1.{{overline|7}}:1''' = '''[[16:9]]''' = {{nobr|4<sup>2</sup>:3<sup>2</sup>}}
: Video widescreen standard, used in [[high-definition television]], one of three ratios specified for [[MPEG-2]] video compression. Also used increasingly in personal video cameras. Sometimes this ratio is rounded to 1.78:1.
; '''1.85:1''' = {{nobr|37:20}}
: 35&nbsp;mm American and British widescreen standard for theatrical film. Introduced by [[Universal Pictures]] in May 1953. Projects approximately three [[film perforations|perforations]] ("perfs") of image space per four-perf frame; films can be shot in [[Negative pulldown|3-perf]] to save cost of film stock. Also the ratio of Ultra 16&nbsp;mm. One of two common formats in [[digital cinema]], where it is called "flat".
; '''1.875:1''' = '''15:8'''
: HDTV ratio used by [[Silicon Graphics]] computers in the 1990s, with the resolution being specified as 1920×1024.
; '''{{nobr|1.9:1}}'''
: [[Society of Motion Picture and Television Engineers|SMPTE]]/[[Digital Cinema Initiatives|DCI]] digital cinema basic resolution container aspect ratio. Exact ratio is 256:135 but it is commonly referred to as 1.9:1<ref>{{cite web |title=Picking the Right Aspect Ratio |url=https://simpledcp.com/picking-right-aspect-ratio/ |publisher=Simple DCP |access-date=28 January 2022 |date=January 1, 2018}}</ref><ref>{{cite web |last1=Owen |first1=Aaron |title=Things to Consider Before Making a DCP: Aspect Ratio & Frame Size |url=https://blog.cinematiq.com/things-to-consider-before-making-a-dcp-aspect-ratio-frame-size-1fdb90c744ac |publisher=Cinematiq |access-date=28 January 2022 |date=August 14, 2020}}</ref> or 1.90:1<ref>{{cite web |title=Aspect Ratio Cheat Sheet |url=https://www.wearethefirehouse.com/aspect-ratio-cheat-sheet |publisher=Firehouse Creative |access-date=28 January 2022}}</ref><ref name=Kauffman>{{cite web |last1=Kauffman |first1=Jeffrey |title=''The Wild Goose Lake'' Blu-ray Review |url=https://www.blu-ray.com/movies/The-Wild-Goose-Lake-Blu-ray/269961/#Review |publisher=[[Blu-ray.com]] |access-date=28 January 2022 |date=September 19, 2020 |quote=''The Wild Goose Lake'' is presented on Blu-ray courtesy of Film Movement with an AVC encoded 1080p transfer in 1.90:1.}}</ref> and sometimes 1.896:1.<ref>{{cite web |last=Nowak |first=Arne |date=October 2010 |title=Digital Cinema Technologies from the Archive's Perspective |url=http://www.fiafnet.org/images/tinyUpload/E-Resources/Commission-And-PIP-Resources/TC_resources/Nowak%20-%20Digital%20Cinema%20Technologies%20v2.0%20FIAF-TC_final%20V1.1.pdf |access-date=May 16, 2016 |publisher=International Federation of Film Archives |page=4}}</ref> Used by [[Diao Yinan]]'s ''[[The Wild Goose Lake]]''.<ref name=Kauffman />
; '''[[Univisium|2:1]]''' = '''18:9'''
: Recently popularized by the [[Red Digital Cinema]]. Original SuperScope ratio, also used in [[Univisium]]. Used as a flat ratio for some American studios in the 1950s and abandoned in the 1960s. Also used in recent mobile phones such as the [[LG G6]], [[Google Pixel 2 XL]], [[HTC U11|HTC U11+]], Xiaomi MIX 2S, and [[Huawei Mate 10 Pro]], while the [[Samsung Galaxy S8]], [[Samsung Galaxy Note 8|Note 8]], and [[Samsung Galaxy S9|S9]] use the similar 18.5:9 ratio.
; '''2.165:1''' {{nobr|~ 28:13}}
: Used by the screens of some [[iPhone]] models since 2017, including the [[iPhone X]], XS, XS Max, 11, 11 Pro, and 11 Pro Max.
; '''2.208:1''' {{nobr|~ 11:5}}
: 70&nbsp;mm standard. Originally developed for [[Todd-AO]] in the 1950s. Specified in [[MPEG-2]] as 2.20:1, but hardly used.
; '''2.35:1''' {{nobr|~ 47:20}}
: 35&nbsp;mm anamorphic prior to 1970, used by [[CinemaScope]] ("'Scope") and early [[Panavision]]. The anamorphic standard has subtly changed so that contemporary anamorphic productions are actually 2.39:1,<ref name="anamorphic" /> but often referred to as 2.35:1 anyway, due to old convention. ''(Anamorphic refers to the compression of the image on film to maximize an area slightly taller than standard [[Negative pulldown|4-perf]] [[Academy of Motion Picture Arts and Sciences|Academy]] aperture, but presents the widest of aspect ratios.)'' All Indian [[Bollywood]] films released after 1972 are shot in this standard for theatrical exhibition.{{Clarify|date=August 2022|reason=According to this paragraph, 2.35:1 was replaced by 2.39:1 around 1970 ''and'' Bollywood films since 1972 are in 2.35:1. One of these must be false. If 2.35:1 was replaced by 2.39:1 around 1970, then films since 1972 cannot be in 2.35:1.}}
; '''2.{{overline|370}}:1''' = {{nobr|64:27}} = {{nobr|4<sup>3</sup>:3<sup>3</sup>}}
: TVs were produced with this aspect ratio between 2009 and 2012<ref>Goddard, Louis. [https://www.theverge.com/2012/8/28/3273716/philips-cinema-21-9-tvs-discontinued Philips discontinuing super-wide Cinema 21:9 TVs due to lack of demand]. ''The Verge''. 2012-08-28. Retrieved 2013-03-18.</ref> and marketed as "[[21:9 aspect ratio|21:9 cinema displays]]". But this aspect ratio is still seen on some higher-end monitors, which are sometimes called UltraWide monitors.
; '''2.39:1''' {{nobr|~ 43:18}} = '''{{frac|21|1|2}}:9'''
: 35&nbsp;mm anamorphic from 1970 onwards. Aspect ratio of current [[anamorphic widescreen]] theatrical viewings, commercials, and some music videos. Often commercially branded as [[Panavision]] format or "[[CinemaScope|'Scope]]". One of two common formats in [[digital cinema]], where it is called "scope".
; '''2.4:1''' = {{nobr|12:5}}<nowiki> ~ 21:9</nowiki>
: Rounded notation of 2.39:1 also known as 2.40:1. All film releases may use 800 lines of the 1920×800 resolution resulting in the 2.40:1 aspect ratio of Blu-ray Disc.
; '''2.55:1''' = '''51:20'''
: Original aspect ratio of [[CinemaScope]] before optical sound was added to the film in 1954. This was also the aspect ratio of [[CinemaScope 55]].
; '''2.{{overline|592}}:1''' = '''70:27'''
: [[Cinerama]] at full height (three specially captured 35&nbsp;mm images projected side by side into one composite widescreen image).
; '''2.{{overline|6}}:1''' = '''8:3''' = '''24:9'''
: [[Full frame (cinematography)|Full-frame]] output from Super 16&nbsp;mm negative when an anamorphic lens system has been used. Effectively, an image that is of the ratio 24:9 is squashed onto the native 15:9 aspect ratio of a Super 16&nbsp;mm negative. Also used by [[Kirill Serebrennikov]] for [[Leto (film)|''Leto'']] (2018).
; '''2.76:1''' = '''69:25'''
: [[Ultra Panavision 70]]/[[MGM Camera 65]] (65&nbsp;mm with 1.25× anamorphic squeeze). Used only on a handful of films between 1957 and 1966 and some in the 2010s, for some sequences of ''[[How the West Was Won (film)|How the West Was Won]]'' (1962) with a slight crop when converted to three-strip [[Cinerama]], and films such as ''[[It's a Mad, Mad, Mad, Mad World]]'' (1963) and ''[[Ben-Hur (1959 film)|Ben-Hur]]'' (1959). More recently, [[Quentin Tarantino]] used it for ''[[The Hateful Eight]]'' (2015); [[Gareth Edwards (filmmaker)|Gareth Edwards]] used the process for shooting ''[[Rogue One]]'' (2016), but the image was cropped to 2.39:1 in post; Edwards would later shoot ''[[The Creator (2023 film)|The Creator]]'' (2023) in this ratio.
; '''3.{{overline|5}}:1''' = '''32:9'''
: In 2017, Samsung and Phillips announced "Super UltraWide displays", with aspect ratio of 32:9.
; '''3.6:1''' = '''18:5'''
: In 2016, IMAX announced the release of films in "Ultra-WideScreen 3.6" format,<ref>{{cite web |url=https://www.imax.com/news/voyage-time-imax-experience-ultra-widescreen |title=''Voyage of Time'': The IMAX® Experience in Ultra-Widescreen |publisher=[[IMAX]] |date=Dec 7, 2016 |access-date=April 27, 2018}}</ref> with an aspect ratio of 36:10.<ref>{{cite magazine|url=https://variety.com/2016/film/in-contention/terrence-malick-ultra-wide-voyage-of-time-re-release-1201933834/ |title='Ultra Widescreen' Version of Terrence Malick's 'Voyage of Time' Set for Release |website=[[Variety (magazine)|Variety]] |date=Dec 5, 2016 |access-date=April 27, 2018 |author=Kristopher Tapley}}</ref> Ultra-WideScreen 3.6 video format didn't spread, as cinemas in an even wider ScreenX 270° format were released.<ref>{{Cite news |url=https://filmmakermagazine.com/76652-introducing-screen-x-cinema-in-270-degrees/#.W8DCZ3tKiM9 |title=Introducing Screen X, Cinema in 270 Degrees {{!}} Filmmaker Magazine |last=Aftab |first=Kaleem |work=Filmmaker Magazine |access-date=2018-10-12 |language=en-US}}</ref>
; '''4:1'''
: Rare use of [[Polyvision]], three 35&nbsp;mm 1.{{overline|3}}:1 images projected side by side. First used in 1927 on [[Abel Gance]]'s ''[[Napoléon (1927 film)|Napoléon]]''.<ref>{{cite web | url=https://www.youtube.com/watch?v=Y-01dsXDqGE |title='Kiesza - What Is Love (Official Video)' |website=[[YouTube]] |date=18 August 2014 |access-date=October 10, 2022 }}</ref>
; '''12:1'''
: [[Circle-Vision 360°]] developed by the [[Walt Disney Company]] in 1955 for use in [[Disneyland]]. Uses nine 4:3 35&nbsp;mm projectors to show an image that completely surrounds the viewer. Used in subsequent Disney theme parks and other past applications.

== Aspect ratio releases ==
{{Unreferenced section|date=March 2023}}

=== Original aspect ratio (OAR) ===
''Original Aspect Ratio'' (OAR) is a [[home cinema]] term for the aspect ratio or dimensions in which a [[film]] or visual production was produced, as envisioned by the people involved in the creation of the work. As an example, the film ''[[Gladiator (2000 film)|Gladiator]]'' was released to theaters in the 2.40:1 aspect ratio. It was filmed in [[Super 35]] and, in addition to being presented in cinemas and television in the ''Original Aspect Ratio'' (OAR) of 2.40:1, it was also broadcast without the [[matte (filmmaking)|matte]], altering the aspect ratio to the television standard of 1.33:1. Because of the varied ways in which films are shot, IAR (Intended Aspect Ratio) is a more appropriate term, but is rarely used.

=== Modified aspect ratio (MAR) ===
''Modified Aspect Ratio'' (MAR) is a home cinema term for the aspect ratio or dimensions in which a film was modified to fit a specific type of screen, as opposed to original aspect ratio. Modified aspect ratios are usually either 1.33:1 (historically), or (with the advent of widescreen television sets) 1.43:1 aspect ratio. 1.33:1 was the modified aspect ratio used historically on 4:3 broadcast television and home videotape formats such as VHS and Beta. A modified aspect ratio transfer is achieved by means of [[pan and scan]] or EAR (Expanded Aspect Ratio)/[[open matte]], the latter meaning removing the cinematic matte from a 2.40:1 film to open up the full 1.33:1 frame or from 2.40:1 to 1.43:1 in [[IMAX]]. Another name for it is rescaled aspect ratio.

== Problems in film and television ==
[[File:Windowboxed.jpg|thumb|375px|A [[windowbox (film)|windowboxed]] image]]
{{Unreferenced section|date=March 2023}}
Multiple aspect ratios create additional burdens on directors and the public, and confusion among TV broadcasters. It is common for a widescreen film to be presented in an altered format ([[cropping (image)|cropped]], [[letterboxed]] or expanded beyond the original aspect ratio). It is also not uncommon for [[windowbox (film)|windowboxing]] to occur (when letterbox and pillarbox happen simultaneously). For instance, a 16:9 broadcast could embed a 4:3 commercial within the 16:9 image area. A viewer watching on a standard 4:3 (non-widescreen) television would see a 4:3 image of the commercial with 2 sets of black stripes, vertical and horizontal (windowboxing or the postage stamp effect). A similar scenario may also occur for a widescreen set owner when viewing 16:9 material embedded in a 4:3 frame, and then watching that in 16:9. [[Active Format Description]] is a mechanism used in digital broadcasting to avoid this problem. It is also common that a 4:3 image is stretched horizontally to fit a 16:9 screen to avoid [[pillarbox]]ing but distorts the image so subjects appear short and fat.

Both PAL and NTSC have provision for some data pulses contained within the video signal used to signal the aspect ratio (See ITU-R BT.1119-1 – [[Widescreen signaling]] for broadcasting). These pulses are detected by television sets that have widescreen displays and cause the television to automatically switch to 16:9 display mode. When 4:3 material is included (such as the aforementioned commercial), the television switches to a 4:3 display mode to correctly display the material. Where a video signal is transmitted via a European [[SCART]] connection, one of the status lines is used to signal 16:9 material as well.

== Still photography ==
{{Unreferenced section|date=March 2023}}
Common aspect ratios in [[photography|still photography]] include:

* 1:1 (1.{{overline|0}}:1)
* 16:15 (1.0{{overline|6}}:1)
* 15:14 (1.0{{overline|714285}}:1)
* 14:13 (1.0{{overline|769230}}:1)
* 13:12 (1.08{{overline|3}}:1)
* 12:11 (1.{{overline|09}}:1)
* 11:10 (1.1:1)
* 10:9 (1.{{overline|1}}:1)
* 9:8 (1.125:1)
* 8:7 (1.{{overline|142857}}:1)
* 23:20 (1.15:1)
* 15:13 (1.{{overline|153846}}:1)
* 52:45 (1.1{{overline|5}}:1)
* 7:6 (1.1{{overline|6}}:1)
* 32:27 (1.{{overline|185}}:1)
* 19:16 (1.1875:1)
* 6:5 (1.2:1)
* 11:9 (1.{{overline|2}}:1)
* 27:22 (1.2{{overline|27}}:1)
* 16:13 (1.{{overline|230769}}:1)
* 5:4 (1.25:1)
* 13:10 (1.3:1)
* 4:3 (1.{{overline|3}}:1)
* 27:20 (1.35:1)
* 15:11 (1.{{overline|36}}:1)
* 11:8 (1.375:1)
* 7:5 (1.4:1)
* 10:7 (1.{{overline|42857}}:1)
* 143:100 (1.43:1)
* 23:16 (1.4375:1)
* 36:25 (1.44:1)
* 13:9 (1.{{overline|4}}:1)
* 29:20 (1.45:1)
* 16:11 (1.{{overline|45}}:1)
* 22:15 (1.4{{overline|6}}:1)
* 37:25 (1.48:1)
* 40:27 (1.{{overline|481}}:1)
* 3:2 (1.5:1)
* 32:21 (1.{{overline|523809}}:1)
* 23:15 (1.5{{overline|3}}:1)
* 20:13 (1.{{overline|538461}}:1)
* 14:9 (1.{{overline|5}}:1)
* 25:16 (1.5625:1)
* 11:7 (1.{{overline|571428}}:1)
* 128:81 (1.5{{overline|802469135}}:1)
* 8:5 (1.6:1)
* 13:8 (1.625:1)
* 44:27 (1.{{overline|629}}:1)
* 18:11 (1.{{overline|63}}:1)
* 33:20 (1.65:1)
* 5:3 (1.{{overline|6}}:1)
* 27:16 (1.6875:1)
* 17:10 (1.7:1)
* 128:75 (1.70{{overline|6}}:1)
* 12:7 (1.{{overline|714285}}:1)
* 43:25 (1.72:1)
* 19:11 (1.{{overline|72}}:1)
* 45:26 (1.7{{overline|307692}}:1)
* 26:15 (1.7{{overline|3}}:1)
* 7:4 (1.75:1)
* 53:30 (1.7{{overline|6}}:1)
* 23:13 (1.{{overline|769230}}:1)
* 71:40 (1.775:1)
* 16:9 (1.{{overline|7}}:1)
* 9:5 (1.8:1)
* 38:21 (1.{{overline|809523}}:1)
* 181:100 (1.81:1)
* 29:16 (1.8125:1)
* 20:11 (1.{{overline|81}}:1)
* 11:6 (1.8{{overline|3}}:1)
* 24:13 (1.{{overline|846153}}:1)
* 37:20 (1.85:1)
* 50:27 (1.{{overline|851}}:1)
* 13:7 (1.{{overline|857142}}:1)
* 28:15 (1.8{{overline|6}}:1)
* 15:8 (1.875:1)
* 17:9 (1.{{overline|8}}:1)
* 256:135 (1.8{{overline|962}}:1)
* 19:10 (1.9:1)
* 39:20 (1.95:1)
* 2:1 (2:1)
* 32:15 (2.1{{overline|3}}:1)
* 28:13 (2.{{overline|142857}}:1)
* 13:6 (2.1{{overline|6}}:1)
* 24:11 (2.{{overline|18}}:1)
* 11:5 (2.2:1)
* 20:9 (2.{{overline|2}}:1)
* 9:4 (2.25:1)
* 16:7 (2.{{overline|285714}}:1)
* 23:10 (2.3:1)
* 7:3 (2.{{overline|3}}:1)
* 47:20 (2.35:1)
* 64:27 (2.{{overline|370}}:1)
* 19:8 (2.375:1)
* 12:5 (2.4:1)
* 5:2 (2.5:1)
* 13:5 (2.6:1)
* 27:10 (2.7:1)
* 11:4 (2.75:1)
* 14:5 (2.8:1)
* 20:7 (2.{{overline|857142}}:1)
* 3:1 (3.{{overline|0}}:1)
* 31:10 (3.1:1)
* 25:8 (3.125:1)
* 22:7 (3.{{overline|142857}}:1)
* 256:81 (3.{{overline|160493827}}:1)
* 16:5 (3.2:1)
* 13:4 (3.25:1)
* 33:10 (3.3:1)
* 10:3 (3.{{overline|3}}:1)
* 27:8 (3.375:1)
* 17:5 (3.4:1)
* 7:2 (3.5:1)
* 32:9 (3.{{overline|5}}:1)
* 18:5 (3.6:1)
* 15:4 (3.75:1)
* 19:5 (3.8:1)
* 4:1 (4:1)
Many digital still cameras offer user options for selecting multiple image aspect ratios. Some achieve this through the use of multi-aspect sensors (notably [[Panasonic]]), while others simply crop their native image format to have the output match the desired image aspect ratio.

=== 1:1 ===
1:1 is the classic Kodak image, and is available as a choice in some digital still cameras, and hearkens back to the days of film cameras when the square image was popular with photographers using twin lens reflex cameras. These medium format cameras used [[120 film]] rolled onto spools. The 6 × 6&nbsp;cm image size was the classic 1:1 format in the recent past. 120 film can still be found and used today. Many [[Polaroid Corporation|Polaroid]] [[instant film]]s were designed as square formats. Furthermore, up until August 2015, photo-sharing site [[Instagram]] only allowed users to upload images in 1:1 format. In 2017, Fujifilm added the 1:1 [[Instax#Instax Square|Instax Square]] format to their lineup of instant film cameras.

=== 5:4 ===
Common in large and medium format photography ('6x7' cameras, actual size {{convert|56|x|70|mm|in|abbr=on}}), which fits the common print paper size of {{convert|8|×|10|in|cm|1|abbr=on}} without cropping and is still in common use for prints from digital cameras.

=== 4:3 ===
4:3 is used by most digital [[point-and-shoot camera]]s, [[Four Thirds system]], [[Micro Four Thirds system]] cameras and [[medium format]] 645 cameras. The 4:3 digital format popularity was developed to match the then prevailing digital displays of the time, 4:3 computer monitors. This aspect ratio is also wider than the popular 16:9, thus being very popular among different E-Sports tournaments.
The next several formats have their roots in classic film photography image sizes, both the classic 35&nbsp;mm film camera, and the multiple format [[Advanced Photo System]] ([[Advanced Photo System|APS]]) film camera. The APS camera was capable of selecting any of three image formats, APS-H ("High Definition" mode), APS-C ("Classic" mode) and APS-P ("Panoramic" mode).

=== 3:2 ===
3:2 is used by classic [[135 film|35&nbsp;mm film]] cameras using a 36&nbsp;mm ×  24&nbsp;mm image size, and their digital derivatives represented by [[DSLR]]s. Typical DSLRs come in two flavors, the so-called professional "full frame" (36&nbsp;mm ×  24&nbsp;mm) sensors and variations of smaller, so called "APS-C" sensors. The term "APS" is derived from another film format known as
[[Advanced Photo System|APS]] and the "-C" refers to "Classic" mode, which exposed images over a smaller area (25.1&nbsp;mm × 16.7&nbsp;mm) but retaining the same "classic" 3:2 proportions as full frame 35&nbsp;mm film cameras.

When discussing DSLRs and their non-SLR derivatives, the term APS-C has become an almost generic term. The major camera manufacturers, including [[Canon (company)|Canon]], [[Sony]], and [[Nikon]], each developed and established sensor standards for their own versions of APS-C sized and proportioned sensors. Canon actually developed two standards, APS-C and a slightly larger area APS-H (not to be confused with the APS-H film format), while Nikon developed its own APS-C standard, which it calls [[Nikon DX format|DX]]. Regardless of the different flavors of sensors, and their varying sizes, they are close enough to the original APS-C image size, and maintain the classic 3:2 image proportions that these sensors are generally known as an "APS-C" sized sensor.

The reason for DSLR's image sensors being the flatter 3:2 versus the taller point-and-shoot 4:3 is that DSLRs were designed to match the legacy 35&nbsp;mm SLR film, whereas the majority of digital cameras were designed to match the predominant computer displays of the time, with VGA, SVGA, XGA and UXGA all being 4:3. Widescreen computer monitors did not become popular until the advent of [[HDTV]], which uses a 16:9 image aspect ratio.

=== 16:9 ===
Known as APS-H (30.2&nbsp;mm × 16.7&nbsp;mm), with the "-H" denoting "High Definition", the 16:9 format is also the standard image aspect ratio for HDTV. 16:9 is gaining popularity as a format in all classes of consumer still cameras which also shoot High Definition ([[high-definition video|HD]]) [[video]]. When still cameras have an HD video capability, some can also record stills in the 16:9 format, ideal for display on HD televisions and widescreen computer displays.

=== 3:1 ===
3:1 is yet another format that can find its roots in the APS film camera. Known as APS-P (30.2 × 9.5&nbsp;mm), with the -P" denoting "Panorama", the 3:1 format was used for [[panorama]] photography. The APS-P panorama standard is the least adhered to any APS standard, and panoramic implementation varies with by manufacturer on different cameras, with the only commonality being that the image is much longer than it is tall, in the classic "panorama" style.

Common [[Photo print sizes|print sizes]] in the United States (in [[inch]]es) include 4×6 (1.5), 5×7 (1.4), 4×5 and 8×10 (1.25), and 11×14 (1.27); [[large format]] cameras typically use one of these aspect ratios. [[Medium format|Medium-format]] cameras typically have format designated by nominal sizes in centimeters (6×6, 6×7, 6×9, 6×4.5), but these numbers should not be interpreted as exact in computing aspect ratios. For example, the usable height of [[120 film|120-format roll film]] is 56mm, so a width of 70mm (as in 6×7) yields an aspect ratio of 4:5 — ideal for enlarging to make an 8×10" portrait. Print sizes are usually defined by their portrait dimensions (tall) while equipment aspect ratios are defined by their landscape dimensions (wide, flipped sideways). A good example of this a 4×6 print (6&nbsp;inch wide by 4&nbsp;inch tall landscape) perfectly matches the 3:2 aspect ratio of a DSLR/35&nbsp;mm, since 6/2=3 and 4/2=2.

For analog projection of photographic slides, projector and screen use a 1:1 aspect ratio, supporting horizontal and vertical orientation equally well. In contrast, digital projection technology typically supports vertically oriented images only at a fraction of the resolution of landscape-oriented images. For example, projecting a digital still image having a 3:2 aspect ratio on a 16:9 projector employs 84.3% of available resolution in horizontal orientation, but only 37.5% in vertical orientation.

== See also ==
* [[Active Format Description]]
* [[Index of articles related to motion pictures]]
* [[Paper size]]
* [[Shoot and protect]]
* [[Glossary of video terms]]
* [[Ultrawide formats]]

== Notes ==
{{Notelist}}

== Footnotes ==
{{Reflist}}

== Sources ==
{{commons category|Aspect ratio}}

=== On aspect ratios ===

*{{cite web |url=http://www.necdisplay.com/support/css/monitortechguide/index05.htm |title=NEC Monitor Technology Guide |access-date=2006-07-24 |archive-url = https://web.archive.org/web/20060521000427/http://www.necdisplay.com/support/css/monitortechguide/index05.htm  |archive-date = 2006-05-21}}
*[http://www.widescreen.org/ The Letterbox and Widescreen Advocacy Page]
*[http://www.widescreenmuseum.com/index.htm American Widescreen Museum]
*[http://www.widescreenmuseum.com/widescreen/apertures.htm Widescreen Apertures and Aspect Ratios]
*{{webarchive |url=https://web.archive.org/web/20131207004356/http://aspect.fre3.com |date=December 7, 2013 |title=Aspect – combined aspect ratio, frame size and bitrate calculator }}
* Aspect Ratios Explained: [https://web.archive.org/web/20090624175845/http://www.imdb.com/Sections/DVDs/AspectRatios/ Part 1] [http://www.dvdactive.com/editorial/articles/aspect-ratios-explained-part-two.html Part 2] {{Webarchive|url=https://web.archive.org/web/20130604034240/http://www.dvdactive.com/editorial/articles/aspect-ratios-explained-part-two.html |date=2013-06-04 }}
*[http://bitbucket.co.uk/work/aspect_ratios.html Explanation of TV Aspect Ratio format description codes]
*{{webarchive |url=https://web.archive.org/web/20090624175845/http://www.imdb.com/Sections/DVDs/AspectRatios/ |date=June 24, 2009 |title=IMDb – Number of DVDs for each aspect ratio }}
*[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31993D0424:EN:HTML SCADplus: 16:9 Action plan for the television in the 16:9 screen format – European Union]

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[[Category:Ratios]]
[[Category:Film and video technology]]
[[Category:Picture aspect ratios]]