ERA Calculator (Earned Run Average)
Enter earned runs and innings pitched to get ERA, WHIP, K/9 and BB/9. Innings use baseball notation, so 6.1 means 6 and one third. It also shows how to calculate ERA for partial innings, such as 6.2 innings pitched.
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Formula
ERA = 9 x ER / IPWHIP = (BB + H) / IPK/9 = 9 x K / IP,BB/9 = 9 x BB / IP- Baseball notation:
IP = outs / 3, so 6.1 = 19 outs = 6.333 innings
Worked example
3 earned runs, 6.1 innings (19 outs), 8 strikeouts, 2 walks, 5 hits.
- ERA = 27 x 3 / 19 = 81 / 19 = 4.26
- WHIP = 7 x 3 / 19 = 1.11
- K/9 = 216 / 19 = 11.37
- BB/9 = 54 / 19 = 2.84
When to use it
Use it for a single start, a season or a career. ERA measures runs per nine innings charged to the pitcher, while WHIP, K/9 and BB/9 describe how the pitcher gets there.
Typical values (rules of thumb)
- ERA under 3.00 is excellent, around 4.00 is close to a typical league figure and above 5.00 is poor. The league average changes each season.
- WHIP near 1.00 is excellent and 1.30 is about average.
- K/9 near 9 is good in the modern game.
Common mistakes
- Typing 6.33 or 6.5 for six and a third innings. Use baseball notation, 6.1, where the digit after the point counts outs.
- Using total runs. ERA counts earned runs only, so runs from errors are excluded.
- Judging a pitcher on a few innings. Three earned runs in one inning is an ERA of 27.00 for that inning, which says little about a season.
How it differs from nearby tools
The batting average calculator is for hitters. The win percentage calculator rates team records, not individual pitching.
Frequently asked questions
How do you calculate ERA?
ERA = 9 x earned runs / innings pitched. With 3 earned runs in 6 1/3 innings that is 27 / 6.333 = 4.26.
What does 6.1 innings pitched mean?
In baseball notation the digit after the point counts outs, not tenths: 6.1 is 6 1/3 innings (19 outs) and 6.2 is 6 2/3 (20 outs). Only .0, .1 and .2 are valid, so 6.3 is rejected.
How is WHIP calculated?
WHIP = (walks + hits allowed) / innings pitched. With 2 walks and 5 hits in 6 1/3 innings, WHIP = 7 / 6.333 = 1.11.
What are K/9 and BB/9?
They scale strikeouts and walks to nine innings: K/9 = 9 x K / IP. Eight strikeouts in 6 1/3 innings is 72 / 6.333 = 11.37. ERA counts only earned runs, and this tool uses the MLB nine-inning basis.
What is a good ERA in baseball?
As a rule of thumb, an ERA below 3.00 is excellent, about 4.00 is average and above 5.00 is poor. League scoring varies year to year, so compare a pitcher with that season's league average.
How do you calculate ERA for 6.2 innings pitched?
6.2 means 6 and two thirds innings, or 20 outs. With 3 earned runs ERA = 9 x 3 / (20 / 3) = 27 / 6.667 = 4.05.
What is a good WHIP?
As a rule of thumb, a WHIP near 1.00 is excellent and 1.30 is about average. With 1 walk and 5 hits allowed in 7 innings, WHIP = 6 / 7 = 0.86.