ERA Calculator
ERA is 0 .
ERA Calculation Method
ERA = Earned runs × 9 ÷ Innings pitched
ERA is is a statistic showing how many runs a pitcher would allow if they pitched 9 innings (one full game).
About This Calculator
Earned run average (ERA) is the number of earned runs a pitcher allows per nine innings, and it is the traditional benchmark for pitching quality. Lower is better.
Enter the earned runs allowed and the innings pitched to calculate the ERA.
In practice ERA is always scaled to nine innings, which is why a reliever who allows two earned runs in three innings shows 6.00 while a starter with three earned runs in nine innings shows 3.00. League averages sit near 4.20 in MLB and around 4.50 in the KBO, so anything under 3.50 is a clearly above-average season.
Key Formula:
ERA = (Earned runs × 9) / Innings pitchedFrequently Asked Questions
What is a good ERA?
In modern MLB, an ERA under 3.00 is excellent, 3.00–4.00 is solid, and above 5.00 is poor. League averages sit around 4.00, but they drift with rule changes and the ball in use.
What counts as an earned run?
A run that scores without the help of a fielding error or a passed ball. Unearned runs still count on the scoreboard but are excluded from ERA, which is why a pitcher can allow runs without it affecting the stat.
How is ERA scaled to nine innings?
ERA = (earned runs × 9) / innings pitched. The scaling makes starters and relievers comparable: four earned runs in 12 innings is 3.00, while the same four runs in 4 innings is 9.00. Short outings therefore swing the number far more than long ones.
What is ERA+ and why does it matter?
ERA+ adjusts ERA for the ballpark and the league scoring environment, with 100 set to league average. A 120 means the pitcher was 20% better than average; a 90 means 10% worse. It lets you compare pitchers from different eras and stadiums fairly.
Related Calculators
Sources & last update
2026-10-19