MLB OPS+

OPS+ tells you how much better or worse a hitter is than the league average in the same season: 100 is exactly average, 120 is 20 % better.

How the calculation works

The calculator uses the formula published by Baseball-Reference: OPS+ = 100 × (OBP / lgOBP + SLG / lgSLG − 1). Each component is divided by the league average, the two ratios are added, and 1 is subtracted. That is why OPS+ is not simply player OPS divided by league OPS: getting on base and hitting for power are normalised separately.

OBP (on-base percentage) is (H + BB + HBP) / (AB + BB + HBP + SF). SLG (slugging percentage) is total bases divided by at-bats. Enter both as decimals the way box scores show them, .350 rather than 35 %. League OBP and SLG must come from the same season.

Besides OPS+, you see the player's and league's OPS (OBP + SLG) and a verbal tier: 130 and up is elite, 110–129 above average, 90–109 around league average and below 90 below average. The park adjustment Baseball-Reference applies is not included here.

Worked example

The defaults are a player OBP of .350 and SLG of .450 against league marks of .320 and .410. Ratios: .350 / .320 = 1.0938 and .450 / .410 = 1.0976. OPS+ = 100 × (1.0938 + 1.0976 − 1) ≈ 119, which is above average. The player's OPS is .800 versus .730 for the league.

Things to keep in mind

• Without a park factor, hitters in hitter-friendly parks such as Coors Field come out too high and those in pitcher-friendly parks too low.
• OPS+ swings wildly over small samples; give it at least a few hundred plate appearances before drawing conclusions.
• Baseball-Reference's published numbers use league averages that exclude pitchers and include a park adjustment, so they can differ from your result by a few points.
• OPS+ weights OBP and SLG roughly equally even though OBP is worth more for scoring runs; wRC+ and similar metrics handle that more precisely.