# ERA Calculator (Earned Run Average)

If you're a baseball fan, this ERA calculator might be right up your alley. It finds the value of the Earned Run Average - a metric that measures the effectiveness of a pitcher in a much more accurate way than a simple win-to-lose ratio. Read on to learn the principles of this statistic - what is ERA in baseball, and how to calculate the ERA of an arbitrary player.

## What is ERA in baseball?

To put it simply, it is a measure of a pitcher's effectiveness. It puts his game in the perspective of all nine innings but takes into account the time he has been pitching.

By definition, it is the mean of earned runs given up by a pitcher per the total of innings pitched (9 for a regular game, 7 for softball, and 6 or 7 for little league games). If there are any defensive errors happening in the game, the run is considered unearned and is not taken into account for ERA calculations.

Generally, the lower the ERA score, the better. The lowest career earned run average in history is 1.82, held by Ed Walsh, who played from 1904 to 1917. After the change of rules post-1920, the highest career ERA score (2.21) belongs to Mariano Rivera, who played baseball in years 1995–2013.

## How to calculate ERA?

The formula for calculating ERA is as follows:

`ERA = (earned runs / innings pitched) * game innings`

where:

**Earned runs**is the number of runs scored while the pitcher is on the mound. As mentioned before, a defensive error leads to an unearned run.**Innings pitched**is each full inning (3 outs) that the pitcher has been on the mound. For partial innings, each out pitched counts as 1/3 of an inning.**Game innings**: typically, this value is equal to 9. It can be lower for softball games or little league games. You can change this parameter in the advanced mode.

For example, let's assume that a pitcher has pitched 65 innings and 2 outs and has allowed 15 earned runs. In such a case, you can calculate his ERA score as follows:

- Calculate the number of innings pitched, considering each out as a third of a full inning. In this case,
`innings pitched = 65 + 2/3 = 65.67`

. - Write down the number of innings per game. Let's assume
`game innings = 9`

. - Input these values to the ERA formula:

`ERA = (earned runs / innings pitched) * game innings`

`ERA = (15 / 65.67) * 9`

`ERA = 2.06`

- The ERA score of this pitcher is equal to 2.06.