Earned run average — ERA — is the classic stat for judging a pitcher: it measures how many earned runs he allows, on average, every nine innings. The lower, the better.
How is it calculated?
ERA = (Earned runs × 9) ÷ Innings pitched
Only «earned» runs count: those not caused by defensive errors. If a pitcher allows 3 earned runs in 9 innings, his ERA is 3.00.
What is a good ERA?
| ERA | Level |
|---|---|
| Under 2.50 | Elite / Cy Young contender |
| 2.50 – 3.50 | Very good |
| 3.50 – 4.50 | Average |
| Over 5.00 | Below average |
Examples with players
- Pedro Martínez posted a 1.74 ERA in 2000, one of the greatest seasons in modern history.
- Johan Santana and Luis Tiant are examples of dominant Latino pitchers with elite ERAs.
[Live data — MLB API] Current-season ERA leaders: (filled in automatically).
Leaders and records
- Modern single-season record: Bob Gibson, with 1.12 in 1968.
- Best career ERA (modern era): Mariano Rivera, with 2.21 as a reliever.
Why it matters (and its limits)
ERA is the most widely used metric for comparing pitchers, but it depends on the defense behind them. That’s why sabermetrics uses FIP, which isolates what the pitcher truly controls.
Related stats
Frequently asked questions
What ERA is considered good?
Under 3.50 is very good; below 2.50 is elite.
What is an earned run?
A run that scores without a defensive error being involved.
