ERA Calculator
Enter earned runs and baseball innings notation, then compare the earned-run rate on the standard nine-inning ERA basis or a shorter-game/custom basis.
About this tool
Standard ERA = 9 × earned runs ÷ innings pitched. The selectable 7-, 6- and custom-inning modes scale the same earned-run rate after partial innings are converted to outs.
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 on the standard 9-inning basis: 12 × 9 ÷ 35 = 3.09 ERA.
The alternate 7-, 6- and custom-inning settings change only the rate basis. They do not change the innings actually pitched and do not claim that every league publishes ERA on that basis.
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.
Source
- Office of the Commissioner of Baseball — 2026 Official Baseball Rules (Rules 9.16 and 9.21(e))
- Supports: earned-run determination and the standard nine-inning ERA calculation used by this calculator.
- Reviewed: 19 September 2026.