Case 1
- Earned runs allowed
- 40
- Innings pitched (.1 = one out)
- 180
2.00
Open with these valuesERA Calculator
2.00
Result: 2.00ERA is earned runs per nine innings: nine times the earned runs, divided by the innings pitched. The catch is the innings: 7.2 IP means seven and two-thirds, not 7.2, because the decimal counts outs. This calculator converts before it divides.
Worked examples
Case 2
- Earned runs allowed
- 75
- Innings pitched (.1 = one out)
- 200
3.38
Open with these valuesCase 3
- Earned runs allowed
- 3
- Innings pitched (.1 = one out)
- 7.2
3.52
Open with these valuesHow it's calculated
ERA = (earned runs × 9) ÷ innings pitched
- StepEnter the earned runs allowed; runs that scored on an error do not count.
- StepEnter the innings pitched in thirds — .1 is one out, .2 is two outs.
- StepThe calculator turns .1 into ⅓ and .2 into ⅔ before dividing.
- ResultRead the ERA: earned runs per nine innings, where lower is better.
What this number means
Per nine innings, not per game
ERA scales what a pitcher allowed onto a nine-inning yardstick, which is what puts starters and relievers on the same scale. Nine earned runs over nine innings is an ERA of 9.00.
Only earned runs are charged to the pitcher
A run that scored because of a fielding error or a passed ball is unearned and never reaches the numerator. That is how ERA tries to separate the pitcher from the defence behind him.
The decimal in innings counts outs
Enter 7.2 for seven innings and two outs, which is 7⅔. Read as tenths, three earned runs over those innings would come out at 3.75 instead of the correct 3.52.
Commonly misread
7.2 innings pitched means 7.2 innings.
It means seven innings and two outs, so 7⅔. The decimal counts thirds: a .1 is one out, and the third out rolls the figure to 8.0.
Every run scored against a pitcher raises his ERA.
Only earned runs do. Runs that scored solely because of an error or a passed ball are unearned and stay out of the calculation.
ERA is the runs a pitcher allows per game.
It is per nine innings pitched, whatever the outing looked like. A reliever who works one inning and allows one earned run has an ERA of 9.00.
Reference table
| Earned runs, innings | Where that lands | ERA |
|---|---|---|
| 0, 180 | a season without an earned run | 0.00 |
| 40, 180 | elite, comfortably under 3.00 | 2.00 |
| 75, 200 | close to league average | 3.38 |
| 2, 5.1 | 5⅓ innings, not 5.1 | 3.38 |
| 3, 7.2 | 7⅔ innings, not 7.2 | 3.52 |
| 9, 9 | a rough complete game | 9.00 |
Questions
How do I calculate ERA?
Multiply the earned runs by nine and divide by the innings pitched. A pitcher with 40 earned runs over 180 innings has (40 × 9) ÷ 180 = 2.00.
Why are innings pitched written as decimals like 7.1 or 7.2?
Innings are recorded in thirds, so the decimal counts outs rather than tenths. A .1 means one out, one-third of an inning, and .2 means two outs, two-thirds. So 7.2 innings is seven and two-thirds, and the next out makes it a full 8.0.
What is ERA in baseball?
ERA stands for earned run average — the number of earned runs a pitcher allows per nine innings pitched. It is the most widely quoted measure of pitching, because it puts starters and relievers on the same per-game scale.
What is a good ERA?
Lower is better. As a rough guide an ERA under 3.00 is elite, the high 3s to low 4s sit around league average, and figures above 5.00 mark a struggling pitcher. The thresholds shift with the era of play, the ballpark and the league's run environment.
What is the difference between earned and unearned runs?
An earned run is one the pitcher is held responsible for; an unearned run scored only because of a fielding error or a passed ball. ERA counts earned runs only, which is how it tries to separate the pitcher from the defence behind him.
Sources and last check
Information, not professional advice.