ERA Calculator
Calculate Earned Run Average instantly.
Accurately calculate your baseball ERA from earned runs and innings pitched.
Earned run average
9-inning scale12 ER over 36 innings
ERA 3.00. 12 earned runs over 36 innings.
How your ERA was calculated
- 12Earned runs
- 9Innings per game
- 36Innings pitched
- 3.00ERA
Using outs to avoid rounding: 12 × 27 ÷ 108 outs = 3.00.
ERA scale
Where this ERA sits between zero and one earned run per inning.
What counts as a strong ERA depends on the level, league and season. This scale is a visual aid, not an official standard.
More calculators
Plan the next outing, or the rest of the season
Two companion tools that use the same outs-based math.
How it works
What is ERA?
Earned run average (ERA) is the average number of earned runs a pitcher allows per nine innings. It answers a simple question: if this pitcher threw a full game, how many earned runs would you expect them to give up at their current rate?
An earned run is any run that scores without help from a fielding error or a passed ball. The official scorer decides which runs are earned; unearned runs still count on the scoreboard but are left out of ERA, so a pitcher isn't charged for their defense's mistakes.
ERA formula
ERA = Earned Runs × 9 ÷ Innings Pitched
Because innings are recorded in thirds, the most reliable way to apply the formula is with outs. Nine innings contain 27 outs, so the equivalent formula is ERA = earned runs × 27 ÷ outs. This calculator always works in outs, then rounds the result to two decimal places.
For leagues that play shorter games, replace 9 with the game length — for example earned runs × 7 ÷ innings pitched for seven-inning games.
How to calculate ERA
- Total the earned runs charged to the pitcher. Leave out unearned runs.
- Convert innings pitched to outs. Multiply full innings by 3 and add the digit after the dot: 36.0 is 108 outs, 6.2 is 20 outs.
- Multiply earned runs by 27 (or by 21 for seven-inning games).
- Divide by outs and round to two decimals.
Example: 12 earned runs in 36 innings → 12 × 27 ÷ 108 = 3.00. That's identical to 12 × 9 ÷ 36, because 36 innings is exactly 108 outs.
Baseball innings explained
Innings pitched use baseball notation, not ordinary decimals. The number after the dot counts outs recorded in an unfinished inning: .0 means a complete inning, .1 means one out and .2 means two outs. A third out completes the inning, so 5.2 is followed by 6.0 — there is no 5.3.
| Written as | Means | Outs | Not |
|---|---|---|---|
| 5.0 | 5 innings | 15 | — |
| 5.1 | 5⅓ innings | 16 | 5.1 decimal innings |
| 5.2 | 5⅔ innings | 17 | 5.2 decimal innings |
| 6.0 | 6 innings | 18 | — |
Treating notation as decimals quietly skews the result. With 1 earned run in 6.1 innings, the correct ERA is 1.42; plugging in 6.1 as a decimal gives 1.48. When you add innings together, add outs: 5.2 + 1.1 is 17 + 4 = 21 outs, or 7.0 innings.
ERA examples
Each row below is calculated with the same code that powers the calculator.
| Line | ER | IP | Calculation | ERA |
|---|---|---|---|---|
| Quality start | 3 | 7.0 | 3 × 27 ÷ 21 outs | 3.86 |
| Short start | 2 | 5.2 | 2 × 27 ÷ 17 outs | 3.18 |
| One out into the 7th | 1 | 6.1 | 1 × 27 ÷ 19 outs | 1.42 |
| Complete-game shutout | 0 | 9.0 | 0 × 27 ÷ 27 outs | 0.00 |
| Full season | 45 | 150.1 | 45 × 27 ÷ 451 outs | 2.69 |
| High school season (7-inning) | 10 | 35.0 | 10 × 21 ÷ 105 outs | 2.00 |
The same high school line on a nine-inning scale would be 2.57, which is why it matters to compare ERAs calculated the same way.
ERA vs WHIP
WHIP (walks plus hits per inning pitched) is (walks + hits) ÷ innings pitched. Where ERA counts runs that actually scored, WHIP counts how many batters reached base by a hit or walk, whether or not they came around to score.
The two often move together, but not always: a pitcher who allows plenty of baserunners and strands them can post a low ERA with a high WHIP. Looking at both gives a fuller picture than either alone.
ERA vs FIP
FIP (fielding independent pitching) uses only strikeouts, walks, hit batters and home runs — outcomes that don't involve the fielders — and adds a league constant so the result reads on the same scale as ERA.
ERA describes what happened, including the effects of defense and sequencing. FIP estimates what a pitcher might have allowed with average defense and luck on balls in play. Neither is “the right one”; a large gap between them is a prompt to look closer. Ready to try your own numbers? Back to the ERA calculator.
FAQ
ERA calculator questions
What is an ERA calculator?
An ERA calculator works out a pitcher's earned run average from two numbers: earned runs allowed and innings pitched. This one converts innings to outs first, so baseball notation like 6.1 and 6.2 is handled correctly, and it can scale ERA to 9-, 7- or 6-inning games.
How do you calculate ERA?
Multiply earned runs by 9, then divide by innings pitched. For example, 12 earned runs over 36 innings is 12 × 9 ÷ 36 = 3.00. If the innings include partial innings, convert them to outs first: ERA = earned runs × 27 ÷ outs.
What does 6.1 innings mean?
6.1 innings means six full innings plus one out — 6⅓ innings, or 19 outs. The .1 is a count of outs, not a tenth of an inning, so it should never be used as the decimal 6.1 in a calculation.
What does 6.2 innings mean?
6.2 innings means six full innings plus two outs — 6⅔ innings, or 20 outs. One more out completes the seventh inning, so the next value is 7.0; there is no 6.3.
How is ERA calculated for 7-inning games?
Replace the 9 in the formula with 7: ERA = earned runs × 7 ÷ innings pitched. For example, 10 earned runs over 35 innings is 2.00 on a 7-inning scale, compared with 2.57 on a 9-inning scale. Many high school, youth and softball stat services use the 7-inning version, so check which one your league uses before comparing numbers.
Can I calculate ERA from earned runs and innings pitched?
Yes. Earned runs and innings pitched are the only inputs ERA needs, plus the game length if your league doesn't play nine innings. Hits, walks and strikeouts aren't part of the formula.
Are unearned runs included in ERA?
No. Runs that score because of a fielding error or a passed ball are ruled unearned by the official scorer and are left out of ERA. They still count on the scoreboard and in a pitcher's runs allowed.
What is the difference between ERA and WHIP?
ERA measures earned runs allowed per nine innings. WHIP measures walks plus hits allowed per inning. ERA tracks the runs that actually scored; WHIP tracks how many batters reached base, whether or not they scored.
Can I calculate my new ERA after a game?
Yes. Add the game's earned runs to your season total, add the game's innings (as outs, so 5.2 + 1.1 = 7.0), then recalculate. The ERA Predictor on this site does this for you and shows how much your ERA moves.
What is a good ERA?
It depends on the level, league and season. A useful comparison is your league's average ERA over the same period — adjusted stats like ERA+ exist for exactly this reason. The same ERA can be excellent in one league and ordinary in another.