Slugging percentage (SLG) measures a hitter's power by weighting each hit by the number of bases it earns — a single counts 1, a double 2, a triple 3 and a home run 4. It is not a true percentage but the name stuck.
Enter singles, doubles, triples, home runs and at-bats to calculate SLG.
Total bases do all the work: 20 singles, 10 doubles, 2 triples and 8 home runs in 200 at-bats gives (20 + 20 + 6 + 32) / 200 = .390. A league average is roughly .400, .500 signals a strong power season and .600 is MVP territory.
SLG = (1B + 2×2B + 3×3B + 4×HR) / ABAbout .400 is league average, .450 is good and .500 or better marks a genuine power hitter. Slugging percentages are read to three decimals, just like batting average.
Batting average treats every hit the same, while slugging gives extra-base hits more weight. Two players with identical .300 averages can have very different slugging percentages if one hits far more home runs.
ISO (isolated power) is SLG minus AVG and measures extra-base power only. A hitter with a .550 SLG and a .280 AVG has an ISO of .270, well above the league average of roughly .150. It strips out singles so power is visible on its own.
Total bases sit in the numerator and at-bats in the denominator, so a player whose hits are almost all home runs can exceed 1.000. A single at-bat that produces a home run gives exactly 4.000 — a real value, but meaningless as a sample.
2026-10-19