⚾ ERA (Earned Run Average) Calculator
Calculate ERA from earned runs and innings pitched.
ERA Formula
ERA = (Earned Runs × 9) / Innings Pitched
Enter innings as decimals. Example: 5⅓ innings → 5.333
ERA Standards
2.00 or below: Elite / 3.00 or below: Excellent / 4.00 or below: Average / 5.00 or above: Poor
Worked Examples
18 earned runs in 54 innings is 18 × 9 / 54 = 3.00.
Two earned runs over 6⅓ innings is 2 × 9 / 6.333 = 2.84, which is why innings are recorded in thirds.
What ERA Hides
Only earned runs count, so runs from errors or passed balls stay out and the official scorer decides what is earned. ERA ignores the ballpark, the defence behind the pitcher and inherited runners, which is why ERA+ and FIP were created. Note that innings are written in thirds, not decimals.
Frequently Asked Questions
- Why is an inning written as 6.1 or 6.2?
- The digit after the point counts outs, not tenths: 6.1 means six and one third innings, 6.2 means six and two thirds. Convert to 6.333 or 6.667 before using the formula.
- What counts as a good ERA?
- Under 3.00 is excellent, 3.00-3.99 is solid, 4.00-4.99 is below average for a starter and above 5.00 is poor. Relievers are judged more strictly because they work fewer innings.
- Does ERA account for the ballpark?
- No. A 3.50 ERA in a pitcher-friendly park can be worth more than 3.00 in a hitter-friendly one, which is what park factors and ERA+ adjust for.