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.
58 earned runs across 180⅔ innings = 2.89.
ERA = (earned runs × 9) ÷ innings pitched
Famous single-season ERAs (live-ball era)
- 1.12Bob Gibson · 1968
- 1.53Dwight Gooden · 1985
- 1.56Greg Maddux · 1994
- 1.74Pedro Martínez · 2000
Earned runs times nine over exact innings, graded against the great pitching seasons — then draft an all-time nine below.
Numbers this good belong on a roster. Draft an all-time nine and run the season.
ROUND 01
SPIN THE ERA
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ModeStats on every card.
Roster12 picks · seats read the era they come from
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Teams
Erasevery era on the board
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The rules
01SPIN
Every spin lands a franchise era — anywhere greatness happened. One legend era guaranteed per run.
02DRAFT
12 seats, your order — tap any open seat to spin it. Every pick flips the card: the honors, the rings, the real numbers.
03SURVIVE
A hundred sixty-two regular-season games, wire to wire — every lineup and rotation seat counts. Go 162-0 and you’re immortal.
10,666player-seasons
1871–todaya century and a half
162games to survive
Guess the Player questions
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.