On-Base Percentage Calculator
On-base percentage measures how often you avoid making an out, counting walks and hit-by-pitches alongside hits.
How OBP is calculated
OBP = (H + BB + HBP) ÷ (AB + BB + HBP + SF)The denominator is at-bats plus walks plus hit-by-pitches plus sacrifice flies — not plate appearances exactly. Sacrifice bunts are excluded, which is the detail most calculators get wrong.
A sacrifice fly lowers your OBP while leaving your batting average untouched, because it counts in this denominator but isn't an at-bat.
Full definition: What is on-base percentage?
Frequently asked questions
- What is a good on-base percentage in slowpitch?
- The tracked rec-league aggregate is .578. Slowpitch OBP runs high because batting averages are high and defences are weaker than in baseball.
- Why is my OBP lower than my batting average?
- That happens when you have sacrifice flies but few walks — sacrifice flies enlarge the OBP denominator without adding to the numerator, while they're excluded from batting average entirely.
- Are sacrifice bunts included in OBP?
- No. Sacrifice bunts are excluded from the OBP formula, unlike sacrifice flies which are included in the denominator.
Track this automatically
Slug Stats works out your OBP — and your spray chart, season totals and team stats — from at-bats you log in seconds. Free on iOS, Android and the web.