Definitions

# On-base percentage

In baseball statistics, on-base percentage (OBP) (sometimes referred to as on-base average [OBA], as the statistic is rarely presented as a true percentage) is a measure of how often a batter reaches base for any reason other than a fielding error, fielder's choice, dropped/uncaught third strike, fielder's obstruction, or catcher's interference (the latter two are ignored as either times-on-base (TOB) or plate appearances in calculating OBP). OBP is added to slugging average to determine on-base plus slugging (OPS). It first became an official MLB statistic in 1984.

## Overview

Traditionally, the best leadoff hitters in the game have high on-base percentages. The league average for on-base percentage has varied considerably over time; in the modern era it is around .340, whereas it was typically only .300 in the dead-ball era. On-base percentage can also vary quite considerably from player to player. The record for the highest career OBP by a hitter, based on over 3000 plate appearances, is .482 by Ted Williams. The lowest is by Bill Bergen, who had an OBP of .194.

Though extremely unlikely, it is possible for a player's on-base percentage to be lower than his batting average (H/AB). However very few players in major league history fall into this category, with the majority of them having under 100 ABs, as it requires having almost no walks or times hit by pitch, with a relatively higher number of sacrifice flies (e.g. if a player has 2 hits in 6 at bats with a sacrifice fly, his batting average would be .333, but his on-base percentage would be .286). An example of this phenomenon would be the Hall-of-Fame pitcher Phil Niekro's hitting statistics from 1982. In 87 AB he never walked, but had four sacrifice hits, leading to a Batting Average of .195 and an OBP of .193.

On-base percentage is calculated using this formula:

$OBP = frac\left\{H+BB+HBP\right\}\left\{AB+BB+HBP+SF\right\}$

where

NOTE: Sacrifice flies were not counted as an official statistic until 1954. Before that time, all sacrifices were counted as sacrifice hits (SH), which included both sacrifice flies and bunts. Bunts (sacrifice hits since 1954), which would lower a batter's on-base percentage, are not included in the calculation for on-base percentage, as bunting is an offensive strategy – often dictated by the manager – the use of which does not necessarily reflect on the batter's ability and should not be used to penalize him. For calculations of OBP before 1954, or where sacrifice flies are not explicitly listed, the number of sacrifice flies should be assumed to be zero.

### All-time leaders

# Player OBP Team(s) Year(s)
1 Ted Williams .4817 Boston Red Sox 19391960
2 Babe Ruth .4740 Boston Red Sox, New York Yankees, Boston Braves 19141935
3 John McGraw .4657 Baltimore Orioles, St. Louis Cardinals, New York Giants 18911906
4 Billy Hamilton .4552 Kansas City Cowboys, Philadelphia Phillies, Boston Beaneaters 18881901
5 Lou Gehrig .4474 New York Yankees 19231939
6 Barry Bonds .4443 Pittsburgh Pirates, San Francisco Giants 19862007
7 Bill Joyce .4349 Brooklyn Ward's Wonders, Boston Reds, Brooklyn Grooms, Washington Senators, New York Giants 18901898
8 Rogers Hornsby .4337 St. Louis Cardinals, New York Giants, Boston Braves, Chicago Cubs, St. Louis Browns 19151937
9 Ty Cobb .4330 Detroit Tigers, Philadelphia Athletics 19051928
10 Todd Helton .4284 Colorado Rockies 1997September 28, 2008
11 Jimmie Foxx .4283 Philadelphia Athletics, Boston Red Sox, Chicago Cubs, Philadelphia Phillies 19051942, 19051942
12 Tris Speaker .4280 Boston Red Sox, Cleveland Indians, Washington Senators, Philadelphia Athletics 19071928
13 Albert Pujols .4250 St. Louis Cardinals 2001-September 28, 2008
14

Eddie Collins .4244 Philadelphia Athletics, Chicago White Sox, Philadelphia Athletics 19061930
15 Ferris Fain .4241 Philadelphia Athletics, Chicago White Sox, Detroit Tigers, Cleveland Indians 19471955

bold is active player

### Single Season Leaders

# Player OBP Team Year(s)
1 Barry Bonds .609 San Francisco Giants 2004
2 Barry Bonds .582 San Francisco Giants 2002
3 Ted Williams .551 Boston Red Sox 1941
4 Babe Ruth .542 New York Yankees 1923
5 Barry Bonds .529 San Francisco Giants 2003
6 Babe Ruth .528 New York Yankees 1920
7 Ted Williams .526 Boston Red Sox 1957
8 Billy Hamilton .517 Philadelphia Phillies 1894
9 Barry Bonds .515 San Francisco Giants 2001
10 Ted Williams .512 Boston Red Sox 1954

## Notes

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