ERA Calculator

• •Use the ERA Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
• •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
• •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
• •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.

Earned Run Average (ERA) is the standard measure of pitching effectiveness in baseball. It represents the average number of earned runs a pitcher allows per nine innings pitched, providing a normalized comparison across pitchers with different workloads. An ERA below 3.00 is considered excellent in modern MLB, while the league average typically falls between 3.80 and 4.50. ERA excludes unearned runs (those resulting from fielding errors), focusing specifically on the pitcher's responsibility. This calculator divides earned runs by innings pitched and multiplies by 9 to scale the result to a full nine-inning game. ERA has been the primary pitching statistic since the early 1900s and remains central to evaluating pitcher performance alongside more modern metrics like FIP and xERA.

• !Including unearned runs in the calculation; only earned runs count.
• !Not converting baseball innings notation (.1 = 1/3 inning) to proper decimals.
• !Comparing ERAs across different ballparks without adjustment; Coors Field inflates ERA by roughly 20%.