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Free calculator

On-base percentage (OBP) calculator

On-base percentage is (hits + walks + hit by pitch) ÷ (at-bats + walks + hit by pitch + sacrifice flies). 42 hits, 18 walks, and 3 hit by pitch in 137 at-bats with 2 sacrifice flies is 63 ÷ 160 = .394.

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On-base percentage calculator

Runs in your browser. Nothing you type is sent to us, saved, or put in analytics.

Showing an example. Change any field to use your own numbers.

All hits, including doubles, triples, and home runs.

Include intentional walks.

Blank counts as 0.

Official at-bats. Walks, hit by pitch, and sacrifices are not at-bats.

Sacrifice bunts do not count here. Blank counts as 0.

Your answer

On-base percentage

.394

On base 63 times in 160 plate appearances that count

Fill in the fields to see the answer.

  1. Times on base63 hits + walks + hit by pitch42 + 18 + 3
  2. Plate appearances that count160 at-bats + walks + hit by pitch + sacrifice flies137 + 18 + 3 + 2
  3. OBP.394 times on base ÷ plate appearances that count63 ÷ 160

On-base percentage for times on base and plate appearances (at-bats + walks + hit by pitch + sacrifice flies)

Times on base20 PA50 PA100 PA200 PA400 PA600 PA
5.250.100.050.025.013.008
10.500.200.100.050.025.017
201.000.400.200.100.050.033
35–.700.350.175.088.058
50–1.000.500.250.125.083
80––.800.400.200.133
120–––.600.300.200
200–––1.000.500.333

How to calculate OBP

Add the times a hitter reached base on their own: hits, walks (intentional ones too), and hit by pitch. Divide by at-bats plus walks plus hit by pitch plus sacrifice flies.

Two things are left out on purpose. Reaching on an error or a fielder's choice does not count as reaching base. Sacrifice bunts are not in the denominator at all, while sacrifice flies are.

Questions

Why are sacrifice flies in the OBP formula but not bunts?

That is how the official rule is written. A sacrifice fly counts against the hitter in on-base percentage. A sacrifice bunt does not appear in either part of the fraction.

Can OBP be lower than batting average?

Yes, rarely. A hitter with no walks or hit by pitch and a few sacrifice flies can end up with an OBP a little below their batting average.

Is my data stored?

No. The math runs in your browser and nothing you type is sent anywhere or put in analytics.

Sources

Formulas and rules checked against these sources on October 28, 2026. Leagues and associations change their rules, so when your league's rulebook differs, follow your league.

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