In baseball, isolated power or ISO is a sabermetric computation used to measure a batter's raw power.
One formula is slugging percentage minus batting average.
{\displaystyle ={\frac {{\mathit {TB}}-H}{AB}}}
{\displaystyle ={\frac {({\mathit {1B}})+(2\times {\mathit {2B}})+(3\times {\mathit {3B}})+(4\times {\mathit {HR}})}{AB}}-{\frac {H}{AB}}}
{\displaystyle ={\frac {({\mathit {2B}})+(2\times {\mathit {3B}})+(3\times {\mathit {HR}})}{AB}}}
The final result measures how many extra bases a player averages per at bat.
A player who hits only singles would thus have an ISO of 0.
The maximum ISO is 3.000, and can only be attained by hitting a home run in every at-bat.
The term "isolated power" was coined by Bill James, but the concept dates back to Branch Rickey and his statistician Allan Roth.