⚾ ERA Calculator
Compute a pitcher's earned run average using earned runs and innings pitched.
Use baseball decimals (.1 = 1 out, .2 = 2 outs). Example: 7⅔ innings = 7.2.
How to Use This Calculator
Enter Earned Runs
Use the total number of earned runs allowed. Exclude unearned runs caused by errors.
Enter Innings Pitched
Type innings pitched using baseball decimals (.1 = one out, .2 = two outs). The tool converts them automatically.
Click Calculate ERA
Press the button to compute ERA instantly. You will see the ERA number and a performance tier.
Review the Summary
Compare your ERA to the benchmark ranges below to understand the result.
Formula
ERA = (Earned Runs × 9) ÷ Innings Pitched
Earned run average estimates how many earned runs a pitcher allows over the course of a full nine-inning game. Only earned runs count toward ERA—runs scored because of errors or passed balls are excluded.
Variables
- Earned Runs (ER): Runs scored without the aid of an error or passed ball.
- Innings Pitched (IP): Official innings recorded; 3 outs equal one inning.
Example
A pitcher allows 32 earned runs in 125.1 innings. Convert 125.1 to 125.33 repeating. ERA = (32 × 9) ÷ 125.33 = 2.30.
Understanding ERA
ERA has been the standard pitching stat since the early 1900s. It measures how effective a pitcher is at preventing earned runs. Lower numbers are better, but context matters—league offensive levels, ballpark factors, and defensive support all influence ERA.
Typical Benchmarks
- < 2.50: Cy Young level dominance
- 2.50 – 3.50: All-Star caliber
- 3.50 – 4.00: Strong rotation arm
- 4.00 – 5.00: Back-end starter / average
- > 5.00: Needs improvement or small sample
Limitations of ERA
ERA can fluctuate due to defensive errors that extend innings, bullpen inheritance, or luck on balls in play. Modern analysis often pairs ERA with metrics like FIP, WHIP, and Statcast expected stats to get a fuller picture.
Frequently Asked Questions
What is an earned run?
An earned run results from hits, walks, and other standard offensive events. If a runner scores because of an error or passed ball, the run is unearned and excluded from ERA.
How do I convert innings with outs?
Baseball scorekeeping uses .1 for one out (1⁄3 inning) and .2 for two outs (2⁄3 inning). Enter innings in that format and the calculator will handle the conversion.
Does ERA include unearned runs?
No. Unearned runs are excluded. However, inherited runners that score after a reliever exits still count against that pitcher’s ERA.
How many innings are needed for a reliable ERA?
Small samples can swing ERA wildly. Analysts often look for 40–60 innings before drawing conclusions about a reliever and 120+ innings for starters.
What’s the difference between ERA and ERA+?
ERA+ adjusts ERA for ballpark and league context, with 100 being average. A pitcher with an ERA+ of 120 is performing 20% better than league average after adjusting for context.