How to Calculate ERA in Baseball
ERA (Earned Run Average) measures a pitcher's effectiveness by showing the average number of earned runs they allow per nine innings pitched. Calculating ERA helps evaluate pitching performance, compare players, and make strategic decisions. Our calculator simplifies this process, providing instant results while helping you understand the mathematics behind this crucial baseball statistic.
ERA Calculator
ERA Formula
ERA = (Earned Runs × 9) ÷ Innings Pitched
Calculation Process
- Count all earned runs allowed by the pitcher
- Count total innings pitched
- Multiply earned runs by 9
- Divide result by innings pitched
- Round to two decimal places
ERA Examples
| Earned Runs | Innings | ERA |
|---|---|---|
| 3 | 9 | 3.00 |
| 5 | 6 | 7.50 |
| 2 | 7 | 2.57 |
FAQs
What counts as an earned run?
Earned runs are runs that score without the aid of errors or passed balls. They're directly attributable to the pitcher's performance.
Why multiply by 9 in ERA calculation?
Baseball games are typically 9 innings long. Multiplying by 9 standardizes the ERA to reflect runs allowed per full game.
How to calculate ERA for relief pitchers?
Use the same formula. For partial innings, convert to decimal (e.g., 1.1 innings = 1.33).
What's considered a good ERA?
In MLB, ERA below 4.00 is generally good. Under 3.00 is excellent, while above 5.00 is poor.
Does ERA include unearned runs?
No. ERA only counts earned runs. Unearned runs are tracked separately.