ERA Calculator (Earned Run Average)
Calculate a pitcher's earned run average from earned runs and innings pitched.
How to use the era calculator
- Enter earned runs allowed and innings pitched.
- Set innings per game (9 for baseball, 7 for softball).
- Click Calculate for the ERA.
Earned versus unearned runs
ERA counts only earned runs — those not caused by fielding errors — so it isolates the pitcher's own performance from defensive mistakes behind them.
How ERA summarises a pitcher
Earned run average expresses how many earned runs a pitcher allows per nine innings, the length of a standard game. Calculated as earned runs times nine divided by innings pitched, it lets you compare pitchers who have thrown very different numbers of innings on a common scale.
What ERA leaves out
ERA excludes unearned runs from errors, which is fair, but it is still influenced by defence, ballpark, and luck. Modern analysts complement it with FIP and WHIP to isolate what a pitcher controls. As a headline number, though, ERA remains the most recognised measure of run prevention.
Frequently asked questions
How is ERA calculated?
ERA = (earned runs × innings per game) ÷ innings pitched. It expresses how many earned runs a pitcher allows per full game.
What is a good ERA?
Under 3.00 is excellent for a starter, around 4.00 is average, and above 5.00 is poor in Major League Baseball.
What is a good ERA?
Below 3.00 is excellent, around 4.00 is roughly league average in modern baseball, and above 5.00 is poor for a regular starter.
What is the difference between earned and unearned runs?
Earned runs are charged to the pitcher; unearned runs result from fielding errors or passed balls and are excluded from ERA.
Why use ERA instead of total runs allowed?
ERA standardises to nine innings, so you can fairly compare pitchers who have thrown different amounts. Raw run totals favour those who pitched fewer innings.
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