What is OBP?
On-base percentage is the rate a hitter avoids making an out: (H + BB + HBP) ÷ (AB + BB + HBP + SF). It is the most valuable triple-slash line because an out is baseball's scarcest resource — teams built on OBP outscore teams built on AVG over 162 games.
How the calculator works
Enter the five inputs and the tool returns OBP with league context. Sacrifice bunts are excluded by rule; sacrifice flies count in the denominator.
Common use cases
- Leadoff hitter evaluation
- Fantasy OBP leagues (an increasingly common format)
- Moneyball-style roster arguments
Formula & context
.340+ is good, .380+ is star level, and .400 over a season is the all-time conversation. League average floats near .320.
Frequently Asked Questions
Why are sacrifice flies in the denominator?
Rule quirk — they are scoring plays that cost an out, so the formula charges them as an at-bat equivalent.
What is a good OBP?
.340+ is solid; .380+ is star level; .400+ for a season is historic.
Is OBP better than AVG?
Almost always — a walk and a single have nearly identical run value.
Privacy & Your Data
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