ERA Calculator
Calculate baseball earned run average from earned runs and innings pitched, including correct .1 and .2 out notation.
About This Tool
ERA = 9 × earned runs ÷ innings pitched. Internally, partial innings are converted to outs before division.
The result is rounded to two decimal places. No performance category is assigned because context varies.
Calculations run locally in your browser. ToolBullet does not transmit these tool inputs.
Baseball innings notation is not decimal notation
Five innings and one out is entered as 5.1 and equals 16 outs. Five innings and two outs is 5.2 and equals 17 outs. A .3 suffix is invalid because the third out completes the next whole inning.
12 earned runs over 35.0 innings: 12 × 9 ÷ 35 = 3.09 ERA.
ERA has limits
ERA depends on official scoring and can be affected by defence, ballpark, league environment, role and sample size. It is not a complete measure of pitching performance.
Definition reviewed 2026-06-23: MLB earned run average glossary.