Baseball
ERA Calculator
Calculate earned run average (ERA) from earned runs and innings pitched.
Informational only — not a substitute for official league statistics or professional judgment.
How it's calculated
Assumptions
- Uses 9 innings per game by default (MLB/NCAA standard) — adjustable for leagues that play a different game length, such as 7-inning youth or doubleheader formats.
- Innings pitched must be entered in standard baseball notation (.0, .1, or .2 for 0, 1, or 2 outs) — not tenths of an inning.
Source: Official Baseball Rules, Rule 9.15 (ERA)
Last reviewed: July 2026
Frequently asked questions
What counts as an earned run?
An earned run is any run that scores without the help of a defensive error or passed ball — runs that would have scored through normal play. The official scorer, not the pitcher's own count, determines which runs are earned in a given game.
Why does innings pitched use .1 and .2 instead of normal decimals?
Baseball box scores record partial innings in thirds, not tenths: .1 means one out recorded (1/3 of an inning) and .2 means two outs recorded (2/3 of an inning). This calculator converts that notation to real innings automatically before computing ERA.
What's considered a good ERA?
In modern MLB, a starting pitcher's ERA below 3.50 is considered very good and below 3.00 is excellent; league-average ERA typically sits in the low-to-mid 4.00s, though the exact bar shifts year to year with league-wide offensive levels.
How is ERA different from WHIP or FIP?
ERA measures earned runs allowed per 9 innings. WHIP measures baserunners allowed (walks + hits) per inning, regardless of whether they scored. FIP estimates what a pitcher's ERA "should" look like based only on strikeouts, walks, and home runs — outcomes largely within the pitcher's control, independent of team defense.
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