GameCalc

On-Base Percentage Calculator

How often does the batter reach base?

Hits

Walks (BB)

Hit by Pitch

At-Bats

Sacrifice Flies

OBP

.420

What you entered

Hits: 65Walks (BB): 30Hit by Pitch: 5At-Bats: 200Sacrifice Flies: 3

1
Numerator: H + BB + HBP
65 + 30 + 5= 100
2
Denominator: AB + BB + HBP + SF
200 + 30 + 5 + 3= 238
3
OBP = numerator / denominator
100 / 238= 0.4202
4
Formatted OBP
0.4202 rounded to 3 decimal places= .420

Result

OBP: .420

On-base percentage from the full plate appearance line

OBP counts hits, walks, and hit-by-pitches over at-bats plus walks, hit-by-pitches, and sacrifice flies. Unlike batting average, it rewards drawing a walk.

Hits	Walks	HBP	At-bats	Sac flies	OBP
50	20	1	200	2	.318
150	50	5	500	5	.366
180	40	2	550	6	.371
120	80	10	450	4	.386
100	100	8	400	3	.407

The last two rows are the case for OBP: a hitter with 100 hits in 400 at-bats has a modest .250 average, but 100 walks lift the on-base percentage to .407. League average OBP sits around .320, and .400 over a season is elite.

OBP values walks and HBP

Unlike batting average, OBP credits a batter for walks and hit-by-pitches — it answers the more complete question of 'how often does this player not make an out,' which is why sabermetrics considers it more valuable than batting average alone.

What's a good OBP?

In MLB, a .320 OBP is roughly league average, .370+ is excellent, and .400+ is elite — the all-time single-season record is Barry Bonds' .609 in 2004, when he was walked an absurd 232 times.

Frequently asked questions

A player has 120 hits, 60 walks, 5 HBP, 400 at-bats, and 8 sac flies — what's his OBP?

OBP = (120 + 60 + 5) ÷ (400 + 60 + 5 + 8) = 185 ÷ 473 = .391, which is excellent — well above the MLB average of about .320.

Why do sabermetrics prefer OBP over batting average?

Because not making outs is the most valuable thing a hitter can do. A batter who walks 100 times and hits .250 reaches base more often than a .290 hitter who rarely walks, and reaching base directly correlates with scoring runs.

How is OBP different from OPS?

OBP measures how often a batter reaches base, while OPS adds OBP plus slugging percentage (total bases ÷ at-bats). OPS captures both getting on base and hitting for power in a single number — an OPS of .800+ is above average, .900+ is elite.

Can a player's OBP be lower than their batting average?

Technically yes, but it's extremely rare. It can happen if a player has a very high number of sacrifice flies relative to their walks and HBP, since sac flies increase the denominator in OBP but don't count in batting average.