Isolated Power ISO
ISO stands for isolated power in baseball. Extra bases per at-bat: slugging percentage with the singles taken out, so it measures power alone.
How ISO is calculated
ISO = SLG − AVG = (2B + 2 × 3B + 3 × HR) ÷ AB
A .300 hitter with no power and a .230 hitter with 40 home runs can post the same slugging percentage; ISO pulls them apart. League-wide it has sat near .160 in recent seasons, and .250 is elite.
What counts as a good ISO?
Half of the 250 qualified MLB players in 2026 were at or below .160. Clearing .227 put a season in the top tenth of the league.
- Median
- .160
- Top 10%
- .227
- Leader
- .291
By position, the median was .192 for 1B, .172 for DH, .168 for C, .165 for LF, .159 for RF and .154 for CF.
Qualified: 300+ AB, non-zero, 2026 regular season.