GUIDES · BETSLIP DOCTOR
How can two hitters have the same batting average but different on-base percentages?
Batting average measures hits per at-bat. On-base percentage also reflects qualifying ways to reach base, such as walks and hit-by-pitches, so two hitters with the same hit-to-at-bat ratio can have different OBPs.
For Baseball readers comparing a hitter's standard statistics · Updated
Batting average counts hits
Batting average is calculated by dividing hits by at-bats. It treats each hit as one hit, whether it is a single or a home run.
Walks and hit-by-pitches do not add hits or at-bats, so they do not change that ratio.
OBP includes qualifying ways to reach base
On-base percentage describes how often a batter reaches base through qualifying outcomes. MLB's glossary includes hits, walks and hit-by-pitches, while excluding reaches such as an error or fielder's choice.
Because the measures count different outcomes, the same batting average does not require the same OBP.
Hypothetical comparison
Fictional example: two hitters each collect three hits in ten at-bats, so both have a .300 batting average. If their other outcomes are comparable and one also draws more walks, those walks can give that hitter a higher OBP without changing the .300 average.
Related questions
Do walks count as hits for batting average?
No. Batting average uses hits divided by at-bats; a walk is neither a hit nor an at-bat.
Can reaching on an error raise OBP?
MLB's glossary says reaching on an error is not counted as a time on base for OBP.