Earned Run Average (ERA) Calculator
Calculate earned run average (ERA) for baseball pitchers using earned runs and innings pitched. Free baseball ERA calculator with charts and breakdowns.
About This Calculator
Earned Run Average (ERA) is a fundamental baseball statistic that measures a pitcher's effectiveness by calculating the number of earned runs they allow per nine innings pitched. Coaches, scouts, fantasy baseball managers, broadcasters, and fans use this calculator to evaluate and compare pitcher performance across all levels of baseball and softball. Unlike win-loss records, ERA isolates the pitcher's individual contribution by excluding runs that scored due to defensive errors.
The formula divides total earned runs allowed by innings pitched, then multiplies by the number of innings in a regulation game (typically 9 for MLB). The result is expressed to two decimal places — for example, an ERA of 3.50 means the pitcher allows approximately 3.5 earned runs per nine innings. The calculator includes an adjustable Game Innings field to support different league formats including Little League (6-7 innings), softball (7 innings), and international competitions. The breakdown charts visually compare the input values and show the proportional relationship between earned runs and innings pitched.
Regional Notes: ERA is universally used across professional baseball leagues worldwide including MLB (USA/Canada), NPB (Japan), KBO (South Korea), LMB (Mexico), and all minor league and amateur levels. The formula and interpretation are identical regardless of the league or country. In collegiate baseball (NCAA) and high school baseball, ERA is a standard metric on scouting reports and player evaluations. The standard game innings is 9 for professional baseball, 7 for softball, and 6-7 for Little League.
Frequently Asked Questions
What is ERA in baseball?
ERA (Earned Run Average) is a baseball statistic that measures a pitcher's effectiveness. It represents the mean number of earned runs a pitcher gives up per nine innings pitched. A lower ERA indicates better pitching performance. The formula is ERA = (Earned Runs / Innings Pitched) × Game Innings.
How is ERA calculated?
ERA is calculated using the formula: ERA = (Earned Runs × Game Innings) / Innings Pitched. For a standard 9-inning MLB game, this simplifies to (Earned Runs × 9) / Innings Pitched. Each out counts as 1/3 of an inning. For example, 6 and 2/3 innings pitched would be entered as 6.67.
What is considered a good ERA in MLB?
In MLB, an ERA below 3.00 is considered excellent, between 3.00 and 4.00 is above average, between 4.00 and 5.00 is average, and above 5.00 is below average. An ERA under 2.00 is exceptional and typically achieved only by elite pitchers. The all-time lowest career ERA (post-1920 rules) is 2.21 by Mariano Rivera.
What is the difference between earned runs and unearned runs?
An earned run is a run that was scored entirely through the offense's hitting and base running, without the benefit of a defensive error. An unearned run scores due to a fielding error, passed ball, or another defensive mistake. Only earned runs are used in ERA calculations, making it a more accurate measure of a pitcher's true performance.
How do you enter partial innings pitched?
Innings pitched are entered as a decimal value where each out counts as 1/3 of an inning. For example: 6 full innings = 6.0, 6 and 1/3 innings = 6.33, 6 and 2/3 innings = 6.67. If a pitcher recorded 65 innings and 2 outs, enter 65.67.
Why can game innings be adjusted?
While standard MLB and most professional baseball games are 9 innings, other levels use different game lengths. Little League uses 6 or 7 innings, softball uses 7 innings, and high school games may vary. The Game Innings field lets you adjust for any league or level to ensure accurate ERA calculation.
Who holds the record for lowest career ERA?
Before 1920 rules changes, Ed Walsh holds the lowest career ERA at 1.82 (1904-1917). After the 1920 rule changes, Mariano Rivera holds the modern record at 2.21 (1995-2013). Among active pitchers, Clayton Kershaw has the lowest career ERA at approximately 2.48.
Is ERA still the best measure of pitcher performance?
ERA remains a fundamental pitching metric, but advanced statistics like FIP (Fielding Independent Pitching), xERA (Expected ERA), and WHIP provide additional context. FIP focuses on factors a pitcher directly controls (strikeouts, walks, home runs), while ERA can be influenced by defense and ballpark factors. Most analysts use ERA alongside these metrics for a complete evaluation.