What is the difference between earned and unearned runs?

Earned runs are scored without the benefit of an error or passed ball. Unearned runs result from defensive mistakes and do not count in ERA.

In modern baseball, an ERA below 3.50 is very good for starters. Relief pitchers often have lower ERAs due to shorter appearances.

How do thirds of innings work?

In baseball notation, 6.1 innings means 6 and one-third innings. For ERA calculation, use 6.333. Similarly, 6.2 = 6.667.

Calculate a pitcher earned run average (ERA) from earned runs and innings pitched.

Earned Runs

Innings Pitched

ERA

2.70

Earned Runs per Inning0.300

Earned Runs per 9 Innings2.7

Innings Pitched100.0

ERA vs Earned Runs

ERA = (Earned Runs / Innings Pitched) x 9

ERA normalizes to a 9-inning game so you can compare pitchers with different workloads.

Below 3.00: Excellent (ace-level)

3.00-3.50: Very good

3.50-4.00: Above average

4.00-4.50: Average

Above 5.00: Below average

A pitcher allowed 30 earned runs in 100 innings.

Learn More

Learn how batting average is calculated, what makes a good average, and how it compares to modern baseball statistics like OBP and OPS.