**Overview**

Traditionally, players with the best on-base percentages bat as leadoff hitter. 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.

For small numbers of at-bats, it is possible (though unlikely) for a player's on-base percentage to be lower than his batting average (H/AB). This happens when a player has almost no walks or times hit by pitch, with a higher number of sacrifice flies (e.g. if a player has 2 hits in 6 at bats plus a sacrifice fly, his batting average would be .333, but his on-base percentage would be .286). The player who experienced this phenomenon with the most number of at-bats in a season was Ernie Bowman, who over 125 at-bats in 1963 had a batting average of .184 and an on-base percentage of .181.

On-base percentage is calculated using this formula:

where

*H*= Hits*BB*= Bases on Balls (Walks)*HBP*= times Hit By a Pitch*AB*= At bats*SF*= Sacrifice Flies

**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. Sacrifice 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.

Read more about this topic: On-base Percentage