Earned Run Average (ERA) — Definition, Formula & Youth Context

Earned Run Average (ERA) measures how many earned runs a pitcher allows per game. Formula: (Earned Runs ÷ Innings Pitched) × number of innings in a regulation game (6 for most youth leagues, 7 for some, 9 for high school and above). An ERA of 3.00 in a 6-inning game means the pitcher allows 3 earned runs per complete game equivalent. At the youth level, ERA is the most recognized pitching performance stat — but it's also the most misleading below 12U because fielding errors inflate it.

ERA = (Earned Runs ÷ Innings Pitched) × Game Innings

ERA = (Earned Runs ÷ Innings Pitched) × 6

Example: A pitcher who allows 4 earned runs in 8 innings pitched across 3 games:

ERA = (4 ÷ 8) × 6 = 0.5 × 6 = 3.00

Key distinction: Earned vs. Unearned runs. Runs that score because of fielding errors are unearned and don't count in ERA. A run that scores on a passed ball, overthrow, or dropped fly ball is unearned. At the youth level, the official scorer's judgment on earned vs. unearned runs is often inconsistent, which makes ERA unreliable.

ERA is a useful concept — "how many runs does this pitcher give up?" — but the number itself is noisy at younger ages for several reasons:

Defense matters too much. A youth pitcher with a great arm can have a 6.00 ERA because the team commits 4 errors per game. The runs aren't the pitcher's fault, but the earned/unearned distinction is often applied inconsistently.

Small sample sizes. Most youth pitchers throw 15-25 innings per season. Over that span, one bad inning (4 runs) can swing ERA by 1.50+ points. The number jumps around too much to be trusted.

Scoring inconsistency. Who's scoring the game? If it's a parent scorekeeper in the stands, the earned/unearned calls are guesswork. ERA is only as accurate as the scorer.