Calculate isolated power from decimal AVG and SLG or derive ISO from a full hit line while cross-checking batting average, slugging, and extra bases. Use one stat scope; hit totals avoid rounding in published rates.
Isolated Power Formula
Isolated power, abbreviated ISO, measures extra bases per official at-bat. The shortest formula subtracts batting average from slugging percentage:
Because every hit contributes one base to both AVG and SLG logic, subtracting AVG leaves only the extra bases earned beyond a single.
ISO From Hit Totals
The same statistic can be calculated directly from doubles, triples, home runs, and at-bats:
A double adds one extra base beyond a single, a triple adds two, and a home run adds three. Singles therefore do not appear in the numerator.
Example
A hitter with 50 hits, including 10 doubles, 2 triples, and 8 home runs, records 38 extra bases beyond singles. Across 200 at-bats, 38 divided by 200 equals .190. The same stat line has a .250 average and .440 slugging percentage, and .440 minus .250 also equals .190.
How to Use ISO
- ISO isolates extra-base production rather than overall hitting or on-base skill.
- Two hitters can share the same batting average but have very different ISO values.
- ISO does not credit walks, hit-by-pitches, or stolen bases.
- League, park, season, and sample size provide important context for comparison.
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Sources
Major League Baseball. MLB Glossary: Isolated Power (ISO), current edition.
Major League Baseball. MLB Statistical Definitions for ISO and slugging percentage, current edition.
