ERA Calculator
Compute earned run average for baseball pitchers from earned runs and innings pitched with performance ratings.
About ERA Calculator
The ERA Calculator computes Earned Run Average for baseball pitchers. ERA shows how many earned runs a pitcher allows per nine innings and is one of the most widely used pitching statistics.
ERA Formula
$$\text{ERA} = \frac{\text{Earned Runs} \times 9}{\text{Innings Pitched}}$$Multiplying by 9 standardizes performance to a full game. For example, 27 earned runs over 180 innings gives an ERA of 1.35.
What Counts as an Earned Run?
Earned runs are runs that score without the benefit of a fielding error or passed ball. Unearned runs are excluded from ERA because they are attributed to defensive mistakes rather than pitching performance.
How to Read ERA Values (MLB)
- Under 2.00: elite, Cy Young caliber
- 2.00 - 3.00: very good, often All-Star level
- 3.00 - 4.00: solid major league starter
- 4.00 - 5.00: below average
- Above 5.00: poor performance
Baseball Innings Notation
Partial innings use baseball format: 7.1 means 7 innings and 1 out (7.333 innings), and 7.2 means 7 innings and 2 outs (7.667 innings).
Related Tools
Track hitting performance with the Batting Average Calculator and At Bats Per Home Run Calculator.
Frequently Asked Questions
What is a good ERA in MLB?
An ERA below 3.00 is generally strong, below 2.00 is elite, and above 5.00 is poor. League-average ERA changes by season and run environment.
Why multiply earned runs by 9?
Baseball games are measured in nine-inning units. Multiplying by 9 converts any innings total into runs allowed per standard game length.
What is the difference between earned and unearned runs?
Earned runs count toward ERA. Unearned runs result from errors or passed balls and are not charged to the pitcher's ERA.
How do I enter partial innings?
Use baseball notation: .1 for one out and .2 for two outs. Example: 45.2 means 45 innings and 2 outs.
Can ERA be used for relief pitchers?
Yes. ERA works for starters and relievers, though relievers often pitch fewer innings so small sample sizes can create volatile ERA values early in a season.
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