How is ERA calculated?
Multiply earned runs by nine, then divide by innings pitched. The nine scales everything to a full game, which is why ERA reads as "runs allowed per nine innings".
The number, then the game
Earned run average calculator.
Earned runs times nine over exact innings, graded against the great pitching seasons — then draft an all-time nine below.
Enter the stat line
Example58 earned runs across 180⅔ innings = 2.89.
Your earned run average2.89ace territory in any era
Famous single-season ERAs (live-ball era)
- 1.12Bob Gibson · 1968
- 1.53Dwight Gooden · 1985
- 1.56Greg Maddux · 1994
- 1.74Pedro Martínez · 2000
ERA = (earned runs × 9) ÷ innings pitched
Numbers this good belong on a roster. Draft an all-time nine and run the season.
ROUND 01
SPIN THE ERA
Board setupoptional
ModeStats on every card.
Roster12 picks · seats read the era they come from
Player yearspeak years only
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Teams
Erasevery era on the board
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Today’s BoardToday’s Board — done.A fresh all-time draft — start your streak.See where you rank and pick your next board.PlaySee rankShare feedback / requestEarned runs times nine over exact innings, graded against the great pitching seasons — then draft an all-time nine below.
Questions people actually ask
How do I enter partial innings?
Baseball writes thirds as .1 and .2 — enter 180.2 for 180⅔ innings. The calculator converts to outs under the hood, so the fraction is exact, not a rounding.
What is a good ERA?
The modern league average floats around 4.00. Under 3.00 is a solid front-line starter, under 2.00 is historic — Bob Gibson’s 1.12 in 1968 literally forced baseball to lower the mound.
What is the difference between earned and unearned runs?
Runs that score because of errors or passed balls are unearned and excluded. That is the point of the stat: it tries to isolate what the pitcher gave up on his own.
Was Pedro in 2000 really better than Gibson in 1968?
By raw ERA no — 1.74 against 1.12. Against their leagues, yes: Pedro’s 1.74 came in a season when the average team scored over five runs a game, the largest gap between a pitcher and his era on record.