Baseball ERA Calculator
Earned Run Average (ERA) is the most widely used statistic to evaluate a pitcher's effectiveness. It represents the number of earned runs a pitcher allows per nine innings pitched, normalizing performance across different workloads. ERA was formalized in Major League Baseball rules and remains the standard for comparing pitchers across eras and leagues. Enter the total earned runs allowed and innings pitched (use decimals for partial innings: 6.1 for six innings and one out, 6.2 for six and two outs) to calculate ERA instantly.
ERA formula
ERA = (Earned Runs / Innings Pitched) × 9
Innings pitched with partial outs must be converted: each out is 1/3 of an inning. So 6.1 IP = 6 + 1/3 = 6.333 true innings, and 6.2 IP = 6 + 2/3 = 6.667 true innings. The calculator performs this conversion automatically.
Interpreting ERA
- Under 2.00: Elite, Cy Young Award territory.
- 2.00 to 3.00: Excellent, top-of-rotation starter.
- 3.00 to 4.00: Above average, solid starter.
- 4.00 to 5.00: League-average range for starters.
- Above 5.00: Below average; often a relief or spot-starter role.
ERA context matters: a 4.00 ERA in a pitcher-friendly park may be equivalent to a 3.50 ERA in a hitter-friendly stadium. Advanced metrics like ERA+ or FIP adjust for these factors.
Baseball ERA calculator: frequently asked questions
What is ERA in baseball?
ERA stands for Earned Run Average. It measures how many earned runs a pitcher allows per nine innings pitched. A lower ERA indicates better pitching performance. The MLB average ERA typically falls between 4.00 and 4.50.
What is the ERA formula?
ERA = (Earned Runs / Innings Pitched) * 9. For example, a pitcher who allows 3 earned runs over 6 innings has an ERA of 4.50.
What is a good ERA in baseball?
An ERA under 3.00 is considered excellent at the MLB level. An ERA between 3.00 and 4.00 is above average. An ERA between 4.00 and 5.00 is average. An ERA above 5.00 is below average for a starting pitcher.
What is the difference between earned runs and unearned runs?
Earned runs are runs that score due to the pitcher's own actions, such as hits or walks. Unearned runs result from fielding errors or passed balls. Only earned runs count in ERA calculations.
How do partial innings affect ERA?
Partial innings are recorded as fractions. One out equals 1/3 of an inning (0.333...), two outs equal 2/3 (0.667). Enter 6.1 for six innings and one out, or 6.2 for six innings and two outs. The calculator handles these correctly.
Official sources
- MLB Official Baseball Rules: mlb.com/official-information/official-rules.
- Society for American Baseball Research (SABR): sabr.org.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.