Earned Run Average (ERA) equals earned runs divided by innings pitched, multiplied by 9. The formula is ERA = (ER / IP) × 9. This normalizes earned runs to a standard 9-inning game. Only earned runs count; runs resulting from errors are excluded from ERA calculation.
- Formula: ERA = (ER / IP) * 9
- MLB average ERA: ~4.23 (2023 season)
- Sub-3.00 ERA: elite starting pitcher territory
- Sub-2.00 ERA: historically dominant (Cy Young caliber)
- Innings pitched .1 and .2 mean 1 and 2 outs, not decimals
| ERA Range | Rating | Example Pitchers | Percentile |
|---|---|---|---|
| Under 2.50 | Elite | deGrom, Scherzer peak | Top 5% |
| 2.50-3.50 | Excellent | Ace-caliber starter | Top 20% |
| 3.50-4.25 | Above Avg | Solid starter | 20-50th |
| 4.25-5.00 | Average | Back-of-rotation | 50-75th |
| 5.00+ | Below Avg | Replacement level | Bottom 25% |
