ERA Calculator (Earned Run Average)

ERA Formula

The following formula is used to calculate an earned run average (ERA).

• Earned runs are determined by the official scorer under the applicable scoring rules, including errors and passed balls.
• Innings pitched is measured in thirds: a box-score 6.1 means 6⅓ innings and 6.2 means 6⅔.
• Game innings is the ERA normalization basis, usually 9 for baseball or 7 for softball; it is not the actual length of a shortened or extra-inning game.

This calculator can determine an ERA for any inning count, for example, 4-inning ERA, 5-inning ERA, 6-inning ERA, 8-inning ERA, and so on.

ERA Definition

Earned run average is earned runs allowed per specified innings basis in baseball or softball. Lower ERA means fewer earned runs per that basis. Use the official scorer’s earned-run count.

Innings Per Sport

• Baseball ERA = 9 Innings
• Softball ERA = 7 Innings
• Cricket uses bowling average and economy rate, not this ERA convention.

How to calculate ERA?

We will now go over an example of calculating the ERA for a pitcher.

1. First, we need to determine the total earned runs of the pitcher. As mentioned previously, this does not include runs due to errors. These are runs that occurred because of a teammate making an error such as dropping a ball. For this example we will assume the total runs to be 5 runs.
2. Next, we need to determine the total innings pitched. Exclude innings pitched by another pitcher, such as a reliever. For this example our pitcher pitched 6 innings.
3. Determine what sport you are playing and determine the total innings in the game. For this, we are assuming it’s baseball, so the innings is 9.
4. Finally enter all the values into the formula

ERA = (5/ 6) * 9 = 7.50

That’s not a terribly good ERA for a starting pitcher in the MLB. For reference the lead ERA in the MLB for the year 2018 was 1.89. This is much lower than the 7.50 above. An ERA this high would likely get you cut from the team!

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