ERA Calculator
Earned run average scales a pitcher's earned runs to a full game. Choose your game length (9, 7, or 6 innings) and enter innings in baseball notation — 6.2 means 6⅔.
How it works
ERA = (earned runs × innings per game) ÷ innings pitched. Innings are stored internally as outs so partial innings are exact. Lowering the game length lowers ERA proportionally, which is why a 7-inning ERA looks better than the same runs over a 9-inning scale.
Worked example
22 earned runs over 68⅓ innings (68.1 IP) on a 9-inning scale: (22 × 9) ÷ 68.333 = 2.90. The same line on a 7-inning scale is (22 × 7) ÷ 68.333 = 2.25.
| Tier | ERA |
|---|---|
| Excellent | Under 3.00 |
| Above average | 3.40 – 3.70 |
| Average | ≈ 4.00 |
| Below average | 4.20 |
| Poor | 4.50+ |
Frequently asked questions
Related tools
Batting Average Calculator
Find a batting average from hits and at-bats.
On-Base Percentage Calculator
Calculate OBP from hits, walks, hit-by-pitch and plate appearances.
Slugging Percentage Calculator
Work out slugging percentage from total bases and at-bats.
OPS Calculator
Add on-base and slugging to get OPS, the all-in-one hitting number.
Sources
- MLB.com — Earned Run Average
- MLB.com — Standard & Advanced Stats Glossary
- FanGraphs — Sabermetrics Library
- Baseball Reference — Glossary
Last reviewed March 1, 2025. Rules and manufacturer charts change — verify against current official sources each season.