How to calculate ERA
Count the earned runs charged to the pitcher. Turn innings pitched into a plain number: each out is one third of an inning, so 7.2 in a box score means 7 and 2/3, about 7.67. Divide earned runs by that number, then multiply by the innings in a full game.
The multiplier is the only thing that changes between baseball and softball. Major League Baseball uses 9. Softball and many youth leagues play 7, so their ERA is 7 × ER ÷ IP. Compare pitchers only when they use the same multiplier.
Earned runs versus total runs
A run is unearned when it would not have scored without an error or a passed ball. The official scorer decides. If your scorebook only has total runs, the calculator will still do the arithmetic, but the answer is a run average, not an ERA.
Questions
How do you calculate ERA with partial innings?
Convert the outs to thirds. 5.1 innings is 5 and 1/3 (5.33) and 5.2 is 5 and 2/3 (5.67). Then divide earned runs by that number and multiply by 9. The calculator does the conversion for you.
What is a good ERA?
It depends on the level and the season. ERA is best used to compare pitchers in the same league and year, because hitting strength and park size change what a typical number looks like.
How do you calculate ERA in softball?
Use 7 instead of 9: ERA = 7 × earned runs ÷ innings pitched. Pick the 7-inning option above.
Is my data stored?
No. The math runs in your browser and nothing you type is sent anywhere or put in analytics.
Sources
Formulas and rules checked against these sources on October 28, 2026. Leagues and associations change their rules, so when your league's rulebook differs, follow your league.