Calculating your earned run average is straightforward once you know the ERA formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the ERA Calculator.
What is ERA?
The ERA calculation tells you your earned run average from a few simple inputs. The figure you are solving for here is the earned run average.
The ERA formula
The core formula is:
Earned run average = Earned runs allowed × 9 ÷ Innings pitchedHere is what each input means:
- Earned runs allowed — a number. Example: 30.
- Innings pitched — a number. Example: 180.
How to calculate it step by step
- Write down the earned runs allowed (for example, 30).
- Write down the innings pitched (for example, 180).
- Apply the formula above to get your earned run average.
- Double-check the result with the ERA Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Earned runs allowed | 30 |
| Innings pitched | 180 |
| Earned run average | 1.50 |
With earned runs allowed of 30 and innings pitched of 180, the earned run average works out to 1.50.
Example 2
With earned runs allowed of 60 and innings pitched of 180, the earned run average works out to 3.00.
| Result | Value |
|---|---|
| Earned run average | 3.00 |
Example 3
With earned runs allowed of 15 and innings pitched of 180, the earned run average works out to 0.75.
| Result | Value |
|---|---|
| Earned run average | 0.75 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the ERA Calculator does it instantly, for free, with the formula and a worked example built in.
Related calculators
Continue exploring sports calculators with these tools: Running Cadence Calculator, Swimming Laps Distance Calculator, Cricket Batting Average Calculator, Bowling Economy Rate Calculator, Cricket Strike Rate Calculator.