View source for On-base percentage

{{short description|Hitting statistic in baseball}}
[[File:1939 Ted Williams.png|thumb|right|Ted Williams is the all-time Major League Baseball leader in on-base percentage.]] 
In [[baseball statistics]], '''on-base percentage''' ('''OBP''') measures how frequently a [[batting (baseball)|batter]] reaches [[base (baseball)|base]]. An official [[Major League Baseball]] (MLB) statistic since 1984, it is sometimes referred to as '''on-base average''' ('''OBA'''),{{efn|Not to be confused with opponents' batting average (OBA), more commonly known as [[batting average against]] (BAA).}} as it is rarely presented as a true [[percentage]].

Generally defined as "how frequently a batter reaches base per [[plate appearance]]",<ref name="Glossary"/> OBP is specifically calculated as the ratio of a batter's [[times on base]] (the sum of [[Hit (baseball)|hit]]s, [[base on balls|bases on balls]], and times [[hit by pitch]]) to the sum of [[at bat]]s, bases on balls, hit by pitch, and [[sacrifice fly|sacrifice flies]].<ref name="Glossary">{{cite web |title=Glossary / Standard Stats / On-base Percentage (OBP)  |url=http://www.mlb.com/glossary/standard-stats/on-base-percentage  |work=MLB.com |access-date=13 June 2018}}</ref> OBP does not credit the batter for reaching base on [[error (baseball)|fielding errors]], [[fielder's choice]], [[uncaught third strike]]s, [[Obstruction (baseball)|fielder's obstruction]], or [[catcher's interference]], and deducts from plate appearances a batter intentionally giving himself up in a [[sacrifice bunt]]. 

OBP is added to [[slugging average]] (SLG) to determine [[on-base plus slugging]] (OPS). 

The OBP of all batters faced by one pitcher or team is referred to as "on-base against".

On-base percentage is calculable for professional teams dating back to the first year of [[National Association of Professional Base Ball Players]] competition in 1871,<ref>{{Cite web |title=Yearly League Leaders & Records for On-Base% |url=https://www.baseball-reference.com/leaders/onbase_perc_leagues.shtml |access-date=2020-07-01 |website=Baseball-Reference.com |language=en}}</ref> because the component values of its formula have been recorded in [[Box score (baseball)|box scores]] ever since. 

==History==
The statistic was invented in the late 1940s by [[Brooklyn Dodgers]] statistician [[Allan Roth]] with then-Dodgers general manager [[Branch Rickey]].<ref>{{Cite web|title=What is a On-base Percentage (OBP)? {{!}} Glossary|url=http://m.mlb.com/glossary/standard-stats/on-base-percentage|access-date=2020-07-01|website=Major League Baseball|language=en-US}}</ref><ref>{{Cite web|title=Allan Roth – Society for American Baseball Research|url=https://sabr.org/bioproj/person/allan-roth/|access-date=2020-07-01|language=en-US}}</ref> In 1954, Rickey, who was then the general manager of the [[Pittsburgh Pirates]], was featured in a [[Life (magazine)|Life Magazine]] graphic in which the formula for on-base percentage was shown as the first component of an all-encompassing "offense" equation.<ref>{{Cite magazine|last=Rickey|first=Branch|date=August 2, 1954|title=Goodby to Some Old Baseball Ideas|magazine=Life|url=https://books.google.com/books?id=9FMEAAAAMBAJ&pg=PA78|access-date=July 1, 2020}}</ref> However, it was not named as on-base percentage, and there is little evidence that Roth's statistic was taken seriously at the time by the baseball community at large.<ref>{{Cite book|last=Schwarz|first=Alan|title=The Numbers Game: Baseball's Lifelong Fascination with Statistics|publisher=St. Martin's Press|year=2004|isbn=9780312322229|location=New York|pages=55}}</ref>

On-base percentage became an official MLB statistic in 1984. Its perceived importance jumped after the influential 2003 book ''[[Moneyball: The Art of Winning an Unfair Game|Moneyball]]'' highlighted [[Oakland Athletics]] general manager [[Billy Beane]]'s focus on the statistic.<ref>{{Cite web|date=2009-05-23|title=Prospectus Idol Entry: Why is On Base Percentage King?|url=https://www.baseballprospectus.com/news/article/8938/prospectus-idol-entry-why-is-on-base-percentage-king/|access-date=2020-07-01|website=Baseball Prospectus}}</ref> Many baseball observers, particularly those influenced by the field of [[sabermetrics]], now consider on-base percentage superior to the  statistic traditionally used to measure offensive skill, [[Batting average (baseball)|batting average]],<ref>{{Cite web|title=My plea to mainstream on-base percentage instead of batting average|url=https://www.cbssports.com/mlb/news/my-plea-to-mainstream-on-base-percentage-instead-of-batting-average/|access-date=2020-07-01|website=CBSSports.com|date=16 November 2012 |language=en}}</ref><ref>{{Cite web|title=Stat to the Future: Why it's time to stop relying on batting average|url=https://www.sportingnews.com/us/mlb/news/explaining-sabermetrics-batting-average-criticism-ops-wrc-fangraphs-statcast/1d6p94zlvv3a01kqajw7vzrm3f|access-date=2020-07-01|website=www.sportingnews.com|date=17 August 2017 |language=en}}</ref> which accounts for hits but ignores other ways a batter can reach base.<ref>{{Cite web|title=OBP {{!}} Sabermetrics Library|url=https://library.fangraphs.com/offense/obp/|access-date=2020-07-01}}</ref>

==Overview==
Traditionally, players with the best on-base percentages bat as [[leadoff hitter]], unless they are power hitters, who traditionally bat slightly lower in the [[Batting order (baseball)|batting order]]. The league average for on-base percentage in [[Major League Baseball]] has varied considerably over time; at its peak in the late 1990s, it was around .340, whereas it was typically .300 during the [[dead-ball era]]. On-base percentage can also vary quite considerably from player to player. The highest career OBP of a batter with more than 3,000 [[plate appearance]]s is .482 by [[Ted Williams]]. The lowest is by [[Bill Bergen]], who had an OBP of .194.

On-base percentage is calculated using this formula:<ref>{{cite web| url = https://www.baseball-reference.com/leaders/onbase_perc_career.shtml| title = Baseball reference: OBP}}</ref><ref>{{Cite web|last=Cole|first=Bryan|date=2014-07-17|title=Should the OBP formula include errors?|url=https://www.beyondtheboxscore.com/2014/7/17/5911131/on-base-percentage-obp-formula-include-errors|access-date=2022-01-14|website=Beyond the Box Score|language=en}}</ref><ref name="fangraphs">{{cite web| url = http://www.fangraphs.com/library/offense/obp/| title = Fangraphs}}</ref>

:<math>OBP = \frac{H+BB+HBP}{AB+BB+HBP+SF}</math>

where

*''H'' = [[Hit (baseball)|Hits]]
*''BB'' = [[Base on balls|Bases on Balls (Walks)]]
*''HBP'' = [[Hit by pitch|Hit By Pitch]]
*''AB'' = [[At bat]]
*''SF'' = [[Sacrifice fly]]

In certain unofficial calculations, the denominator is simplified and replaced by [[Plate appearance|Plate Appearance]] (PA); however, the calculation PAs includes certain infrequent events that will slightly lower the calculated OBP (i.e. [[catcher's interference]], and [[sacrifice bunt]]s).<ref name="fangraphs"/> Sacrifice bunts are excluded from consideration on the basis that they are usually imposed by the manager with the expectation that the batter will not reach base, and thus do not accurately reflect the batter's ability to reach base when attempting to do so. This is in contrast with the sacrifice fly, which is generally unintentional; the batter was trying for a hit.<ref name="Glossary"/>

===All-time leaders===
{| class="wikitable sortable" style="border-collapse: collapse;"
|- bgcolor="#E3E3E3" align="center"
| width="12px" | '''#'''
| width="135px" | '''Player'''
| width="50px" | '''OBP'''<ref name=BaseballRefBatAvg>{{cite web |url=https://www.baseball-reference.com/leaders/onbase_perc_career.shtml?redir |title=Career Leaders for On Base Percentage|access-date=2011-06-25 |publisher=Sports Reference, Inc }}</ref>
| width="450px" | '''Team(s)'''
| width="140px" | '''Year(s)'''
|-
|1
|[[Ted Williams]]
|.4817
|[[Boston Red Sox]]
|[[1939 in baseball|1939]]–[[1942 in baseball|1942]], [[1946 in baseball|1946]]–[[1960 in baseball|1960]]
|-
|2
|[[Babe Ruth]]
|.4740
|Boston Red Sox, [[New York Yankees]], [[Boston Braves (baseball)|Boston Braves]]
|[[1914 in baseball|1914]]–[[1935 in baseball|1935]]
|-
|3
|[[John McGraw]]
|.4657
|[[Baltimore Orioles (1882-1899)|Baltimore Orioles]], [[St. Louis Cardinals]], [[New York Giants (NL)|New York Giants]]
|[[1891 in baseball|1891]]–[[1906 in baseball|1906]]
|-
|4
|[[Billy Hamilton (baseball, born 1866)|Billy Hamilton]]
|.4552
|[[Kansas City Cowboys (American Association)|Kansas City Cowboys]], [[Philadelphia Phillies]], [[Boston Beaneaters]]
|[[1888 in baseball|1888]]–[[1901 in baseball|1901]]
|-
|5
|[[Lou Gehrig]]
|.4474
|New York Yankees
|[[1923 in baseball|1923]]–[[1939 in baseball|1939]]
|-
|6
|[[Barry Bonds]]
|.4443
|[[Pittsburgh Pirates]], [[San Francisco Giants]]
|[[1986 in baseball|1986]]–[[2007 in baseball|2007]]
|-
|7
|[[Bill Joyce (baseball)|Bill Joyce]]
|.4349
|[[Brooklyn Ward's Wonders]], [[Boston Reds (1890–1891)|Boston Reds]], [[Brooklyn Grooms]], [[Washington Senators (1891–99)|Washington Senators]], New York Giants
|[[1890 in baseball|1890]]–[[1898 in baseball|1898]]
|-
|8
|[[Rogers Hornsby]]
|.4337
|St. Louis Cardinals, New York Giants, Boston Braves, [[Chicago Cubs]], [[Baltimore Orioles#St. Louis Browns|St. Louis Browns]]
|[[1915 in baseball|1915]]–[[1937 in baseball|1937]]
|-
|9
|[[Ty Cobb]]
|.4330
|[[Detroit Tigers]], [[Philadelphia Athletics]]
|[[1905 in baseball|1905]]–[[1928 in baseball|1928]]
|-
|10
|[[Jimmie Foxx]]
|.4283
|Philadelphia Athletics, Boston Red Sox, Chicago Cubs, Philadelphia Phillies
|[[1925 in baseball|1925]]–[[1942 in baseball|1942]], [[1944 in baseball|1944]]–[[1945 in baseball|1945]]
|-
|11
|[[Tris Speaker]]
|.4279
|Boston Red Sox, [[Cleveland Indians]], [[Washington Senators (1901–1960)|Washington Senators]], Philadelphia Athletics
|[[1907 in baseball|1907]]–[[1928 in baseball|1928]]
|-
|12
||[[Eddie Collins]]
|.4244
|Philadelphia Athletics, [[Chicago White Sox]]
|[[1906 in baseball|1906]]–[[1930 in baseball|1930]]
|}

===Single-season leaders===
{| class="wikitable" style="border-collapse: collapse;"
|- bgcolor="#E3E3E3" align="center"
| width="12px" | '''#'''
| width="135px" | '''Player'''
| width="60px" | '''OBP'''<ref name=SingleSeasonOBP>{{cite web |url=https://www.baseball-reference.com/leaders/onbase_perc_season.shtml |title=Single Season League Leaders for On-Base Percentage|access-date=2011-06-25 |publisher=Sports Reference, Inc.}}</ref>
| width="175px" | '''Team'''
| width="70px" | '''Year'''
|-
|1
|[[Barry Bonds]]
|.6094
|[[San Francisco Giants]]
|[[2004 in baseball|2004]]
|-
|2
|[[Barry Bonds]]
|.5817
|San Francisco Giants
|[[2002 in baseball|2002]]
|-
|3
|[[Ted Williams]]
|.5528
|[[Boston Red Sox]]
|[[1941 in baseball|1941]]
|-
|4
|[[John McGraw]]
|.5475
|[[Baltimore Orioles]]
|[[1899 in baseball|1899]]
|-
|5
|[[Babe Ruth]]
|.5445
|[[New York Yankees]]
|[[1923 in baseball|1923]]
|-
|6
|[[Babe Ruth]]
|.5319
|New York Yankees
|[[1920 in baseball|1920]]
|-
|7
|[[Barry Bonds]]
|.5291
|San Francisco Giants
|[[2003 in baseball|2003]]
|-
|8
|[[Ted Williams]]
|.5256
|Boston Red Sox
|[[1957 in baseball|1957]]
|-
|9
|[[Billy Hamilton (baseball, born 1866)|Billy Hamilton]]
|.5209
|[[Philadelphia Phillies]]
|[[1894 in baseball|1894]]
|-
|10
|[[Babe Ruth]]
|.5156
|New York Yankees
|[[1926 in baseball|1926]]
|}

==See also==
{{Portal|Baseball}}
*[[List of Major League Baseball career on-base percentage leaders]]
*''[[Moneyball: The Art of Winning an Unfair Game]]''

==Notes==
{{notelist}}

==References==
{{Reflist|30em}}

{{Baseball statistics}}

{{DEFAULTSORT:On-Base Percentage}}

[[Category:Batting statistics]]
[[Category:Baseball terminology]]
[[Category:Percentages]]