ERA Calculator
Enter earned runs and innings pitched to compute a pitcher's earned run average. ERA scales runs to a full game, so a lower number means fewer earned runs allowed per nine innings.
How to calculate ERA
- Enter the number of earned runs allowed.
- Enter the innings pitched as a decimal, using thirds for partial innings.
- Keep the game length at 9, or change it for shorter games, and read the ERA.
Examples
30 earned runs over 180 innings
earnedRuns 30, inningsPitched 180
ERA 1.50
Frequently asked questions
How is ERA calculated?
Earned run average is earned runs times the game length, divided by innings pitched. With a 9-inning game, ERA = (earned runs x 9) / innings pitched. For example, 30 earned runs over 180 innings is (30 x 9) / 180 = 1.50.
What does the .1 and .2 in innings pitched mean?
In box scores, innings pitched uses thirds, not tenths. A .1 means one out, or one third of an inning, and .2 means two outs, or two thirds. So 6.2 innings is really 6 and 2/3, which is about 6.667 in decimal form. Enter the decimal value here.
What is an earned run?
An earned run is a run that scores without the help of an error or a passed ball. Runs that score only because of defensive mistakes are unearned and are excluded from ERA.
What is a good ERA?
In modern Major League Baseball, an ERA under 3.00 is excellent, the low 4.00s is around league average and above 5.00 is poor. Context such as ballpark and era of play matters.
Why can I change the game length?
ERA traditionally scales to 9 innings, but some leagues and doubleheaders use 7-inning games. Setting the game length to 7 scales the rate to those shorter games for a fair comparison.
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