Isolated power

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.

$ISO=SLG-AVG$

$=\frac{𝑇𝐵-H}{AB}$

$=\frac{(1𝐵)+(2\times 2𝐵)+(3\times 3𝐵)+(4\times 𝐻𝑅)}{AB}-\frac{H}{AB}$

$=\frac{(1𝐵)+(2\times 2𝐵)+(3\times 3𝐵)+(4\times 𝐻𝑅)-(1𝐵+2𝐵+3𝐵+𝐻𝑅)}{AB}$

$=\frac{(2𝐵)+(2\times 3𝐵)+(3\times 𝐻𝑅)}{AB}$

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.

See also

• PECOTA

References

• Baseball Prospectus Glossary
• Baseball Simple : Isolated Power (ISO) Calculator
• FanGraphs Sabermetrics Library