1. What is ERA?

ERA (Earned Run Average) is a statistic in baseball that measures a pitcher's effectiveness, calculated as the average number of earned runs given up by a pitcher per nine innings pitched.

2. How Does the Calculator Work?

The calculator uses the ERA formula:

Where:

• Earned Runs — Runs for which the pitcher is held accountable
• Innings Pitched — Number of innings the pitcher has completed
• 9 — Standard number of innings in a regulation game

Explanation: The formula normalizes the earned runs to a standard 9-inning game for comparison across pitchers.

3. Importance of ERA

Details: ERA is one of the most important statistics for evaluating pitcher performance. Lower ERA values indicate better performance.

4. Using the Calculator

Tips: Enter earned runs (count) and innings pitched (can include fractions like 6.2 for 6⅔ innings). Both values must be valid (earned runs ≥ 0, innings pitched > 0).

5. Frequently Asked Questions (FAQ)

Q1: What's considered a good ERA?
A: In modern MLB, ERA below 4.00 is generally good, below 3.00 is excellent, and below 2.00 is exceptional.

Q2: How does ERA+ differ from ERA?
A: ERA+ adjusts for ballpark factors and league average, where 100 is average and higher is better.

Q3: What's the difference between earned and unearned runs?
A: Earned runs are those that score without the benefit of errors or passed balls. Unearned runs result from defensive errors.

Q4: Can ERA be calculated for partial innings?
A: Yes, innings pitched can include fractions (e.g., 6.1 = 6⅓, 6.2 = 6⅔).

Q5: Why multiply by 9 in the formula?
A: This standardizes the measurement to a full 9-inning game, allowing comparison between starters and relievers.