Our Earned Run Average calculator helps pitchers, coaches, and fans quickly convert earned runs and innings pitched (or outs pitched) into a precise ERA.
ERA Calculator
What Is ERA in Baseball?
Earned Run Average (ERA) measures the average number of earned runs a pitcher allows per nine innings. It’s a key pitching metric tool used at every level—from baseball history to modern MLB analytics—to compare pitcher effectiveness fairly.
How to Calculate ERA?
Enter Earned Runs (integer ≥ 0).
Input Innings Pitched (decimal, e.g. 5.2 for 5⅔ innings) or toggle to Use Outs Pitched (integer ≥ 0) which we convert by dividing by 3.
Set Innings per Game (default 9, editable for 7‑inning games).
Click Calculate to get ERA = (Earned Runs / Innings Pitched) × Innings per Game, rounded to two decimals.
Baseball History & ERA
The concept of ERA dates back to the early 1900s, as teams sought fair comparisons between pitchers with different workloads. Over decades, ERA+ and advanced pitching analytics have built on this foundational ERA formula.
Major League Baseball & ERA Leaderboards
In MLB, ERA remains a headline stat. From Walter Johnson’s pristine marks in 1913 to modern aces topping leaderboards, ERA continues to define pitching greatness.