ERA Calculator

LAST UPDATE: September 24th, 2020


Definition – What is Earned Run Average?

ERA is the number of runs a pitcher allows for every 9 innings of play (7 innings for some leagues). The lower the number, the fewer runs the pitcher allows.

ERA is adjusted to the number of innings a pitcher has played. It is seen as more accurate than a win/loss ratio.

A pitcher with an ERA of 3.00 typically allows 3 runs for every 9 innings of play. (If the pitcher is in a league with 7 regulation innings, they would allow 3 runs for every 7 innings of play.

Formula – How to calculate ERA

ERA = (Earned Runs Allowed ÷ Innings Pitched) x Innings in a Regulation Game

Each out that is pitched counts as 1/3 of an inning.

Most professional level games are nine innings. Softball games are typically seven innings, and little league games are often six or seven innings.

An ERA is listed to 2 decimal points.


If a pitcher has pitched 98 innings and 1 out and has allowed 28 Earned Runs, then:
ERA = (28 ÷ (98 + 1/3)) x 9
ERA = (28 ÷ 98.333) x 9
ERA = 0.28475 x 9
ERA = 2.5627
Therefore, the pitcher’s ERA is 2.56

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