earned run average

baseball statistic

Also known as: ERA

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Last updated

July 15, 2026

Quick Summary

The earned run average (ERA) is a key statistic in baseball used to measure a pitcher's performance. It represents the average number of earned runs a pitcher allows per nine innings pitched.1

To calculate ERA, you divide the total number of earned runs scored against a pitcher by the total number of innings they have pitched. This result is then multiplied by nine.1

For example, if a pitcher allows 3 earned runs in 6 innings, their ERA would be calculated as (3 earned runs / 6 innings pitched) * 9 = 4.5. This statistic helps fans and analysts understand how effectively a pitcher prevents the opposing team from scoring. The term ERA is also an abbreviation for the Equal Rights Amendment.12

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Mariano Rivera
…652 saves, with a career earned-run average (ERA) of 2.21. Moreover, when he retired in 2013, Rivera had a lifetime adjusted ERA (ERA+; an ERA adjusted for opponents and ballparks, with the average major-league pitcher set at 100) of 205, far and away the highest ERA+ ever.
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…652 saves, with a career earned-run average (ERA) of 2.21. Moreover, when he retired in 2013, Rivera had a lifetime adjusted ERA (ERA+; an ERA adjusted for opponents and ballparks, with the average major-league pitcher set at 100) of 205, far and away the highest ERA+ ever.
Read More