How to Calculate ERA in Baseball

Earned Run Average (ERA) is the most universally recognized statistic for evaluating a pitcher's effectiveness. But if you don't have a computer handy, you might be wondering exactly how to calculate ERA manually. Luckily, the math is straightforward.

The Standard Formula: How is ERA Calculated?

To understand how is ERA calculated, you just need three pieces of information: the total earned runs allowed, the number of innings pitched, and the regulation length of the game (which is 9 innings in standard baseball).

Here is the exact formula for calculating ERA baseball stats:

Step-by-Step Example

Let's say you want to know how to calculate ERA in baseball for a starting pitcher who gave up 3 earned runs over 6.1 innings (which is 6 innings and 1 out, or 6.333 innings mathematically).

1. Multiply the Earned Runs (3) by 9 = 27.
2. Divide that result (27) by the exact innings pitched (6.333).
3. The resulting ERA is 4.26.

If you don't want to convert partial outs into decimals yourself, the easiest way to find how to calculate ERA baseball stats is to just use our free ERA Calculator. It automatically converts extra outs and instantly outputs your exact Earned Run Average.