What is On-Base Percentage?

On-Base Percentage measures how often a batter reaches base via a hit, walk, or hit-by-pitch. It is calculated as (H + BB + HBP) divided by (AB + BB + HBP + SF) and is a better measure of offensive value than batting average because it counts walks.

What is the difference between OBP and batting average?

Batting average only counts hits divided by at-bats, ignoring walks and hit-by-pitches. OBP includes those ways of reaching base and uses a wider denominator, so a patient hitter with many walks can have a far higher OBP than batting average.

How is Slugging Percentage calculated?

Slugging is total bases divided by at-bats, where total bases weight singles as 1, doubles as 2, triples as 3, and home runs as 4. It measures power and extra-base impact rather than just whether a batter reached base.

OPS is On-Base Percentage plus Slugging Percentage, combining the ability to reach base with the ability to hit for power into one number. An OPS above .900 is excellent, around .750 is average, and below .650 is poor for a regular hitter.

Why are sacrifice flies in the OBP denominator but not at-bats?

A sacrifice fly is not charged as an at-bat in batting average, but it does count as a plate appearance where the batter failed to reach base, so it is added to the OBP denominator. Sacrifice bunts are excluded entirely by rule.

Baseball On-Base Percentage Calculator

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Batting average undersells patient hitters by ignoring walks. On-Base Percentage and Slugging together — summarised as OPS — give a far truer picture of offensive value. This calculator applies the exact MLB formulas, including the subtle role of sacrifice flies in the OBP denominator.

How it works

The three statistics build on each other from a single batting line:

OBP = (H + BB + HBP) / (AB + BB + HBP + SF)
TB  = singles + 2×doubles + 3×triples + 4×home runs
SLG = TB / AB
OPS = OBP + SLG

Singles are derived as hits minus the extra-base hits, so you only enter total hits plus the doubles, triples, and home runs. Sacrifice flies count in the OBP denominator but never as at-bats.

Example and tips

A batter with 400 at-bats, 130 hits (28 doubles, 3 triples, 22 home runs), 60 walks, 5 hit-by-pitches, and 6 sacrifice flies has an OBP of (130 + 60 + 5) / (400 + 60 + 5 + 6) = 195 / 471 ≈ .414, total bases of 231, a SLG of .578, and an OPS near .992 — an elite season. Make sure your extra-base-hit counts never exceed total hits, or the singles figure goes negative.