ERA Calculator
Calculate a pitcher’s earned run average from earned runs and innings pitched, with partial innings and 7- or 9-inning games.
How it works
ERA = earned runs × innings per game ÷ innings pitched
ERA scales a pitcher’s earned runs to a full game, so pitchers with different workloads compare fairly. Baseball’s ".1" and ".2" notation means thirds of an inning — one out and two outs — not tenths, which is the classic mistake when computing ERA by hand. Unearned runs (those set up by errors or passed balls) are excluded.
Worked example
65 earned runs in 180 innings of 9-inning baseball: 65 × 9 ÷ 180 = 3.25. With two extra outs (180.2 innings, 180.67 exact) it would be 65 × 9 ÷ 180.67 = 3.24.
Frequently asked questions
Why can’t I just type 180.2 innings?
Because 180.2 in baseball notation means 180⅔ innings, not 180.2 exactly. The extra-outs dropdown converts the notation correctly — one out adds 0.333 innings, two outs add 0.667.
What is a good ERA?
In today’s MLB: under 3.00 is front-of-rotation, roughly 4.00 is league average, and above 5.00 struggles to hold a job. In 7-inning softball, benchmark numbers differ — compare within your league.
Earned vs unearned runs — who decides?
The official scorer. A run that scores only because of an error or passed ball is unearned and doesn’t count toward ERA, which is why ERA and runs allowed per 9 can differ noticeably.
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This calculator is for educational purposes. Double-check important results before acting on them.