On Base Percentage Calculator

Created by Rita Rain
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Nov 03, 2022

The on-base percentage calculator lets you determine a baseball batter's effectiveness at reaching base. Check if your favorite player is making progress and how well he compares with other athletes. The text below will explain what OBP is, how to calculate on-base percentage, what is OPS (on-base plus slugging), and how it relates to OBP.

What is OBP - on-base percentage?

On-base percentage is a measure of how often a batter reaches base. It is used in baseball statistics to assess whether a player is a good offensive performer or not. OBP is considered a better statistic than batting average because it takes into account hits and walks, whereas BA doesn't. Like slugging percentage, on-base percentage is a misnomer - it is not a percentage, but an average (hence it is sometimes called on-base average).

💡 Measuring a team's performance, we also compare where they stand against different opponents. For that, we use the magic number calculator.

How to calculate on-base percentage?

The formula for OBP is:

OBP = (H + BB + HBP) / (AB + BB + HBP + SF)


  • OBP - on-base percentage.
  • H - hits: the number of times the batter reaches first base.
  • BB - bases on balls (also called walks): the number of times he throws four pitches out of the strike zone, none of which are swung at by the hitter.
  • HBP - hit by pitch: the number of times he is struck by a pitched ball without swinging at it and is awarded first base as a result.
  • AB - at bats: the batter's turns batting against a pitcher.
  • SF - sacrifice flies: the number of times the batter hits a fly-ball out to the outfield or foul territory, allowing a runner to score

To know the OBP of a given player, first add hits, bases on balls, and times hit by pitch together. The sum will be the batter's times-on-base. Then calculate the number of plate appearances - add together at bats, walks, times hit by pitch, and sacrifice flies. Finally, divide the times-on-base by the plate appearances to get the OBP score.

Or you could simply input the values into the on-base percentage calculator - why bother doing the calculations when our perfect, tireless computers can do it for you?

How to interpret the result?

Once you have a number, take a look at the rough comparison below to know if your favorite player is doing well this season:

  • .390 - excellent
  • .370 - great
  • .340 - above average
  • .320 - average
  • .310 - below average
  • .300 - poor
  • .290 - awful

As for the best results in the history of baseball: .609 is the single-season record, held by Barry Bonds, while Ted Williams scored the highest career OBP of .482.

What is OPS - on-base plus slugging?

OPS is a statistic closely related to OBP. It is meant to help evaluate the hitter's effectiveness by combining measures of most important skills - how well a hitter can reach a base and how well he can hit for average and for power. As the name suggests, to know on-base plus slugging, simply add a player's on-base percentage to their slugging percentage. To discover the latter metric, visit Omni's slugging percentage calculator.

Rita Rain
Bases on Balls
Hits by Pitch
At Bats
Sacrifice Flies
On Base Percentage
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