This baseball earned run average calculator converts earned runs and outs pitched into a standard ERA using an innings-per-game base.
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ERA Calculator
Calculate baseball earned run average from earned runs, outs pitched, and game length.
Calculator
About this calculator
Formula notes
innings = whole innings + outs / 3; ERA = earned runs x innings in game / innings.
Worked examples
- Example: 3 earned runs in 6 innings with a 9-inning game gives an ERA of exactly 4.50.
- 3 earned runs, 6 innings, and 2 outs with a 9-inning game gives 6.667 innings and ERA 4.05.
How to use it
- Enter earned runs.
- Enter whole innings and additional outs pitched.
- Review the ERA after setting game-length basis.
Frequently asked questions
How are partial innings counted?
Outs are thirds, so 6 innings and 2 outs becomes 6.667 effective innings for the ERA formula.
Does ERA account for unearned runs?
No, ERA uses earned runs only; unearned runs are removed by the formula, though official record adjustment is more nuanced.
Limits and interpretation
- ERA is affected by the game schedule and record definitions; official statistics depend on scorer decisions and season bookkeeping.
- The result is a run average, not a predictive rating of a pitcher's skill, and does not account for defense, stadium, opponents, era, or league.