What is ERA?
ERA (Earned Run Average) measures a pitcher's effectiveness in baseball. It shows the average number of earned runs a pitcher allows per nine innings pitched. Lower ERA indicates better performance. Teams use ERA to evaluate pitchers' skills, compare players, and make strategic decisions. It's a key statistic in baseball analytics and player contracts.
ERA Formula
ERA = (Earned Runs × 9) ÷ Innings Pitched
Calculator
How to Use
Enter total earned runs allowed by the pitcher in the first field. Input total innings pitched in the second field. Click Calculate to get ERA. Use Clear to reset. The calculator automatically applies the ERA formula. For partial innings, use decimal format (e.g., 6.2 for 6⅔ innings). Result shows with two decimal places for precision.
Calculation Derivation
ERA was created in 1912 by Henry Chadwick. The formula normalizes performance to a 9-inning game standard. Earned runs exclude errors, focusing purely on pitching performance. The ×9 multiplier scales results to full game length. Modern baseball adopted ERA as official statistic in 1913. It remains fundamental in pitcher evaluation across all baseball leagues worldwide.
ERA Table
| Earned Runs | Innings | ERA |
|---|---|---|
| 5 | 9 | 5.00 |
| 3 | 6 | 4.50 |
| 2 | 7 | 2.57 |