How to Calculate an ERA

Earned run average, or ERA, measures the amount of runs a pitcher concedes in baseball per every nine innings. Even if a pitcher does not pitch a full nine innings, ERA calculates how many runs, on average, the pitcher gives up in that span. To calculate ERA, you use the number of runs conceded and the number of innings pitched.

Things You'll Need

  • Runs allowed
  • Innings pitched
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Instructions

    • 1

      Determine the number of earned runs a pitcher conceded and the number of innings the pitcher pitched. For example, in 2009, Yankees pitcher C.C. Sabathia pitched 230 innings and allowed 86 earned runs.

    • 2

      Divide the number of earned runs by the number of innings pitched. In our example, 86 divided by 230 equals 0.373913.

    • 3

      Multiply the number calculated in Step 2 by nine. In our example, 0.373913 times nine equals 3.36527, which rounds to 3.37.