ERA Calculator
What is ERA in Baseball?
Earned Run Average (ERA) is one of the most important statistics used to evaluate a pitcher's performance in baseball. It represents the average number of earned runs a pitcher allows per nine innings pitched. The lower the ERA, the better the pitcher is performing.
How to Calculate ERA
The formula for calculating ERA is:
ERA = (Earned Runs ÷ Innings Pitched) × 9
For example, if a pitcher has allowed 27 earned runs in 81 innings pitched, their ERA would be: (27 ÷ 81) × 9 = 3.00
What is a Good ERA?
| ERA Range | Rating | Description |
|---|---|---|
| Below 2.00 | Excellent | Elite level, Cy Young Award contender |
| 2.00 - 3.00 | Very Good | Top-tier starter or reliever |
| 3.01 - 4.00 | Good | Solid major league pitcher |
| 4.01 - 5.00 | Average | Typical MLB performance |
| Above 5.00 | Below Average | Struggling or inexperienced pitcher |
ERA in Different Contexts
ERA values can vary significantly based on several factors:
- Era: The average ERA in MLB has fluctuated throughout history. During the "Dead Ball Era" (pre-1920), ERAs were typically lower, while during the "Steroid Era" (1990s-early 2000s), ERAs tended to be higher.
- Ballpark: Some stadiums are more "pitcher-friendly" (larger dimensions, higher altitude), while others favor hitters.
- League: The American League typically has slightly higher ERAs due to the designated hitter rule.
- Role: Relief pitchers often have lower ERAs than starters since they pitch fewer innings and can exert maximum effort.
Limitations of ERA
While ERA is a valuable statistic, it has some limitations:
- It doesn't account for the quality of defense behind the pitcher
- It can be significantly affected by a few bad outings
- It doesn't consider the quality of opposition faced
- For relievers who inherit runners, ERA may not fully reflect their performance
This is why advanced metrics like FIP (Fielding Independent Pitching), WHIP (Walks plus Hits per Inning Pitched), and WAR (Wins Above Replacement) are often used alongside ERA for a more complete evaluation of a pitcher's performance.