How to Calculate ERA

Earned runs and innings

ERA is earned runs times 9, divided by innings pitched. Three earned runs over nine innings is 27 ÷ 9, which is 3.00. Two earned runs over seven innings is 18 ÷ 7, which is 2.57.

A box score writes partial innings with a point: 6.1 is 6 innings and 1 out, and 6.2 is 6 innings and 2 outs. Four earned runs in 6.1 innings is 36 ÷ 6⅓, which is 5.68. Use the outs menu for that. This page only does the division.

Questions

How do you calculate ERA?

Multiply earned runs by 9, then divide by innings pitched. 3 earned runs in 9 innings is a 3.00 ERA.

What does 6.1 innings mean?

In a box score, 6.1 means 6 innings and 1 out, which is 6 and 1/3 innings. It does not mean 6.1 as a decimal. 6.2 means 6 innings and 2 outs.

Do unearned runs count in ERA?

Only earned runs go into the formula. This calculator does not decide whether a run is earned.