sports-and-fitness calculator
Earned Run Average Calculator
Calculate baseball ERA from official earned runs, whole innings, and additional outs.
Earned Run Average Calculator
Earned run average
Enter earned runs and innings pitched.
Enter partial innings as additional outs, not decimal tenths.
Formula version 1.0.0
How to use this calculator
- Enter official earned runs.
- Enter completed whole innings.
- Choose zero, one, or two additional outs.
- Calculate ERA per nine innings and review the total-outs conversion.
Symbols and units
| Symbol | Meaning | Unit or domain |
|---|---|---|
ER | Earned runs | runs |
IP | Innings pitched | innings |
O | Total outs recorded | outs |
ERA | Earned run average | runs/9 innings |
Checked examples
Fifty innings
Inputs: 20 earned runs, 50 innings, 0 extra outs
Calculation: ERA = 9×20÷50
Result: 3.60
The pitcher allowed 3.6 earned runs per nine innings at that rate.
Check: earned-run-average.test.ts
Two additional outs
Inputs: 3 earned runs, 6 innings plus 2 outs
Calculation: 20 outs = 20÷3 innings; ERA = 27×3÷20
Result: 4.05
The .2 baseball notation represents two outs, not two-tenths of an inning.
Check: earned-run-average.test.ts
Assumptions, rounding, and limits
- Runs are official earned runs.
- Innings are represented as whole innings plus zero to two outs.
- At least one out was recorded.
- Official scoring decisions are supplied by the user.
Frequently asked questions
Does 6.2 innings mean 6.2 decimal innings?
No. It means six innings and two outs, or 20 total outs.
Are unearned runs included?
No. ERA uses earned runs only.
Why multiply by nine?
ERA standardizes the rate to a nine-inning game.
Sources and review
- MLB.com: Earned Run Average (ERA) — Earned runs per nine innings
- Formula version
- baseball.earned-run-average@1.0.0
- Formula review
- Equatara formula review
- Editorial review
- Equatara editorial review
- Last verified
- 2026-10-25
- Applicability
- Official baseball earned runs and outs; scoring classification excluded.
- Next review
- On material formula/source change, or by 2028-10-25.
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Found a problem?
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