ERA Calculator – Earned Run Average
Calculate Earned Run Average (ERA) for baseball pitchers with detailed performance analysis
Calculate ERA (Earned Run Average)
Runs scored while pitcher was on mound (excludes defensive errors)
Complete innings pitched (3 outs = 1 inning)
Each out = 1/3 of an inning
Standard innings per game
ERA Formula
ERA = (Earned Runs ÷ Innings Pitched) × Game Innings
- Earned Runs: Runs scored while pitcher on mound
- Innings Pitched: Full innings + (outs ÷ 3)
- Game Innings: Standard innings per game (usually 9)
ERA Rating Scale
ERA Records
All-Time Career ERA:
- • Ed Walsh: 1.82 (1904-1917)
- • Mariano Rivera: 2.21 (post-1920)
- • Three Finger Brown: 2.06
Lower ERA indicates better pitching performance
Understanding ERA
- •Only earned runs count (not defensive errors)
- •Each out counts as 1/3 of an inning
- •Lower ERA = better pitching performance
- •ERA under 3.00 is considered excellent
Understanding Earned Run Average (ERA)
What is ERA?
Earned Run Average (ERA) is a fundamental statistic that measures a pitcher's effectiveness by calculating the average number of earned runs allowed per nine innings pitched. It's one of the most important metrics for evaluating pitching performance in baseball.
Why is ERA Important?
- •Measures pitcher effectiveness independent of team offense
- •Accounts for defensive errors (unearned runs excluded)
- •Standardized metric for comparing pitchers
- •Key factor in MVP and Cy Young Award voting
Earned vs Unearned Runs
Earned Runs
- • Runs scored due to hits, walks, or wild pitches
- • Pitcher is directly responsible
- • Count toward ERA calculation
- • Result of pitching performance
Unearned Runs
- • Runs scored due to defensive errors
- • Not pitcher's fault
- • Excluded from ERA calculation
- • Result of fielding mistakes
Note: Official scorers determine whether runs are earned or unearned based on whether they would have scored without defensive errors.