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Earned Run Average Calculator.

Calculate earned runs allowed per nine innings.

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Set your values

Results update as you type.

Earned run average: 2.4

Earned run average

0.000000
earnedRuns: 12

earnedRuns

0.000000
inningsPitched: 45

inningsPitched

0.000000

Results update automatically as you type.

Use Cases

Track a pitcher's performance

Use this calculator to quickly compute a pitcher's ERA after a game or across a season, helping you evaluate their effectiveness.

Example: A pitcher allows 3 earned runs in 6 innings: ERA = 3 / 6 * 9 = 4.50.

Compare pitchers

Calculate ERA for multiple pitchers to compare their run prevention ability on an equal scale (per nine innings).

Example: Pitcher A: 2 ER in 5 IP = 3.60 ERA; Pitcher B: 3 ER in 7 IP = 3.86 ERA.

Frequently Asked Questions

What is earned run average (ERA)?
ERA measures a pitcher's effectiveness by showing how many earned runs they allow per nine innings pitched. It is calculated by dividing earned runs by innings pitched and multiplying by nine.
How do I calculate ERA using this calculator?
Enter the number of earned runs allowed and the total innings pitched. The calculator will compute ERA by dividing earned runs by innings pitched and multiplying by nine.
What counts as an earned run?
An earned run is a run scored without the benefit of an error or a passed ball. The official scorer determines which runs are earned. This calculator uses the earned runs you input.

Tips & Common Mistakes

Tips

  • Ensure you enter earned runs, not total runs, to get an accurate ERA.
  • Innings pitched should be entered as a decimal (e.g., 6.2 for 6 2/3 innings) for correct calculation.
  • Use this calculator for quick estimates; official ERA is calculated by the league using precise rules.
  • Remember that a lower ERA indicates better pitching performance.

Common Mistakes to Avoid

  • Entering total runs instead of earned runs, which inflates the ERA.
  • Using innings pitched as whole numbers without converting fractional innings (e.g., 6.2 instead of 6.67).
  • Forgetting to multiply by nine, which would give runs per inning instead of per nine innings.

Last updated: August 13, 2026