Batting average only counts hits. On-base percentage counts every way a batter reaches base without making an out on the play, which makes it a better measure of how often a hitter doesn’t make an out.
How to use the On Base Percentage Calculator#
- Enter hits, walks and hit by pitch. These are the ways a batter reaches base.
- Enter at-bats and sacrifice flies. These go into the bottom of the formula.
- Read the OBP. It appears as a three-digit decimal, like .364.
The formula#
A batter with 150 hits, 60 walks and 5 hit by pitch, in 520 at-bats with 5 sacrifice flies, has an OBP of (150 + 60 + 5) ÷ (520 + 60 + 5 + 5) = 215 ÷ 590 = .364.
What’s a good OBP#
Around .320 is roughly average in modern Major League Baseball, .340 to .360 is good, and anything above .400 is excellent. Only a few players in a generation do it over a full season. League averages change over time, so compare a player with their own era.
What OBP leaves out#
OBP doesn’t distinguish a single from a home run, so it’s usually paired with slugging percentage. Added together they give OPS. Sacrifice bunts and catcher’s interference aren’t counted in the formula.
A worked season#
A hitter finishes the year with 160 hits, 70 walks, 5 hit-by-pitches, 520 at-bats and 6 sacrifice flies. The top of the fraction is 160 + 70 + 5 = 235 times on base. The bottom is 520 + 70 + 5 + 6 = 601 plate appearances that count. OBP is 235 ÷ 601 = 0.391, written .391. The same player’s batting average is 160 ÷ 520 = 0.308. The gap of 0.083 between the two is the value of the walks and hit-by-pitches that batting average ignores.
What the benchmarks look like#
Across Major League Baseball, the league-wide OBP usually sits somewhere around .315 to .330. A figure of .340 to .350 is solid, .370 or more is excellent, and .400 is the mark of a great hitter. Ted Williams holds the career record at .482, and Barry Bonds set the single-season record of .609 in 2004, helped by a record number of intentional walks. A hitter with a modest average but a high walk rate can still be among the most valuable on a team.
| OBP | Rough rating |
|---|---|
| .300 or below | Poor |
| .320 | League average |
| .340 | Above average |
| .370 | Excellent |
| .400 and up | Elite |
Why teams care, and what it leaves out#
Making an out is the one thing a batter must avoid, since each team has only 27 outs in a regular game. OBP measures how often a hitter avoids making one, which is why analysts rate it above batting average for predicting runs. Add slugging percentage, which measures power, and you get OPS. OBP does not distinguish between a single and a home run, and it ignores reaching on an error or a fielder’s choice, which count as at-bats without a hit. It also leaves out sacrifice bunts. Use it with a power measure, not alone. The percentage calculator is handy for turning the decimal into a plain percentage.
Putting OBP next to power#
On-base percentage measures getting on base, and slugging percentage measures power: total bases divided by at-bats. If the hitter in the example has 260 total bases in 520 at-bats, the slugging percentage is .500, and OPS, the sum of the two, is .391 + .500 = .891. An OPS above .800 is generally good, and above .900 is excellent. OPS is a handy summary, though some analysts prefer weighted measures that give OBP more weight.
Frequently asked questions#
Add hits, walks and hit by pitch, then divide by at-bats plus walks, hit by pitch and sacrifice flies.
Because a sacrifice fly is an out that doesn’t count as an at-bat, but it’s still an out, so it counts against OBP.
Around .340 to .360 is good, and over .400 is elite.
It tells you more, because it counts walks and hit by pitch.
A plate appearance is every time a player comes to bat. An at-bat leaves out walks, hit-by-pitches, sacrifice flies and sacrifice bunts. OBP uses almost all plate appearances, except sacrifice bunts, which is why its denominator is at-bats plus walks, hit-by-pitches and sacrifice flies.