What does 'ERA' mean in baseball? What to know about the MLB pitching statistic.

Earned run average, abbreviated ERA, has long been one of baseball's most recognizable statistics, signifying the number of earned runs that a pitcher surrenders per nine innings.

Major League Baseball's top pitchers every year usually have an ERA under 3.00, meaning they give up less than three earned runs for every nine innings they pitch. Unearned runs (due to fielding errors, etc.) do not count towards a pitcher's ERA.

Here's what you need to know about the baseball pitching stat:

What does ERA mean in baseball?

ERA stands for earned run average, which is the number of earned runs that a pitcher gives up per nine innings.

ERA is calculated by dividing a pitcher's number of earned runs allowed by innings pitched, and multiplying by nine. For example, if a pitcher gives up three earned runs in six innings of work, their ERA is 4.50: ([3 ÷ 6] x 9)

Who has the best ERA in baseball history?

Since 1920, Hall of Fame closer Mariano Rivera has the best ERA (2.21) of any pitcher with at least 1,000 innings pitched.

1. Mariano Rivera (Yankees): 2.21 ERA

2. Clayton Kershaw (Dodgers): 2.49 ERA

3. Hoyt Wilhelm (nine teams): 2.52 ERA

4. Jacob deGrom (Mets, Rangers): 2.53 ERA

5. Whitey Ford (Yankees): 2.75 ERA

6. Dan Quisenberry (Royals, Cardinals, Giants): 2.76 ERA

7. Sandy Koufax (Dodgers): 2.76 ERA

8. Ron Perranoski (Dodgers, Twins, Tigers, Angels): 2.79 ERA

9. Bruce Sutter (Cubs, Cardinals, Braves): 2.83 ERA

10. John Hiller (Tigers): 2.83 ERA

What is MLB's league average ERA?

• 2023: 4.33

• 2022: 3.96

• 2021: 4.26

• 2020: 4.44

• 2019: 4.49

• 2018: 4.14

More fun facts on baseball

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• Who invented baseball?

This article originally appeared on USA TODAY: What does ERA mean in baseball? What to know about MLB pitching stat.