ERA Calculator - Earned Run Average
Calculate pitcher's ERA by entering earned runs and innings pitched. Essential tool for evaluating pitching performance in baseball.
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Enter earned runs and innings pitched to calculate ERA
What is ERA
ERA stands for Earned Run Average, and it's the gold standard for measuring how effective a pitcher is at preventing runs. Simply put, it tells you how many earned runs a pitcher gives up, on average, over nine innings of work.
Think of ERA as a pitcher's report card. A lower ERA means fewer runs allowed, which obviously makes you a better pitcher. It's been the go-to pitching statistic since the early 1900s because it focuses on what pitchers can actually control - preventing earned runs.
The key word here is "earned." If your shortstop boots a ground ball and that leads to a run, that doesn't count against your ERA because it wasn't your fault. ERA only counts runs that happened because of hits, walks, hit batters, or other things the pitcher did - not defensive mistakes.
How to Calculate ERA
The ERA calculation is straightforward once you understand what goes into it. You need two numbers: earned runs allowed and innings pitched. Then you scale it up to show what would happen over a full nine-inning game.
Formula
ERA = (Earned Runs ÷ Innings Pitched) × 9
Example
If a pitcher allows 21 earned runs in 37 innings:
(21 ÷ 37) × 9 = 5.11 ERA
Innings pitched can include partial innings. If a pitcher gets two outs in an inning before being removed, that counts as 0.2 innings (since each out is one-third of an inning). One out = 0.1 innings, two outs = 0.2 innings, three outs = 1.0 inning.
The reason we multiply by nine is to standardize everything. Whether a pitcher throws 50 innings or 200 innings, ERA lets you compare them fairly by showing what their performance would look like over a complete nine-inning game.
Frequently Asked Questions
What's considered a good ERA?
In Major League Baseball, an ERA under 3.00 is excellent, 3.00-4.00 is good, 4.00-5.00 is average, and above 5.00 is below average. However, this varies by era and league - the "steroid era" of the late 1990s saw much higher ERAs across the board.
Do unearned runs count toward ERA?
No, unearned runs don't count. If a run scores because of an error, passed ball, or wild pitch, it's unearned and doesn't hurt the pitcher's ERA. The official scorer decides whether a run is earned or unearned.
Can ERA be misleading?
Yes, ERA doesn't tell the whole story. A pitcher might have a low ERA but walk too many batters, or have a high ERA due to bad luck or poor defense. Modern stats like FIP (Fielding Independent Pitching) try to isolate what the pitcher actually controls.
What's the lowest ERA ever recorded?
Ed Walsh holds the modern era record with a 1.82 ERA in 1910. In the live-ball era (1920+), the record is Pedro Martinez's 1.74 ERA in 2000, which was even more impressive given the offensive environment of that time.