How to Calculate ERA in Baseball (And Why It Matters in Sports Betting)
Want to understand ERA and how it impacts your baseball bets? You’re in the right place. ERA, or Earned Run Average, is one of the most important metrics for evaluating a pitcher—and for sharp bettors, it’s essential to know how to calculate it and what it means.
ERA (Earned Run Average) represents the average number of earned runs a pitcher allows over nine innings. It’s a clean way to judge a pitcher’s effectiveness—excluding runs that score due to fielding errors or passed balls.
Important Note for Bettors: Only earned runs count. If a run scores due to a fielding error, it’s not included in ERA.
For sports bettors, ERA—alongside WHIP (Walks + Hits per Inning Pitched)—is one of the two key metrics used to evaluate starting pitchers and bullpens when capping games.
ERA = (Earned Runs × 9) ÷ Innings Pitched
Step-by-step:
- Determine Innings Pitched: Each inning = 3 outs. 6.1 = 6 and 1 out (6⅓), 6.2 = 6 and 2 outs (6⅔). Don’t round up.
- Total Earned Runs Given Up: Add how many earned runs the pitcher allowed.
- Multiply Earned Runs by 9
- Divide by Total Innings Pitched
Example:
Pitcher throws 5.0 innings and allows 3 earned runs.
Step 1: 3 × 9 = 27
Step 2: 27 ÷ 5 = 5.40 ERA
What’s a good ERA?
| ERA Range | Grade | Comment |
|---|---|---|
| 2.00 or lower | Elite | Ace-level, Cy Young contender |
| 2.01–3.00 | Rock-Solid | Top-tier starter |
| 3.01–3.50 | Good | Reliable and effective |
| 3.51–4.50 | Average | Needs support from offense |
| 4.51–5.00 | Below Average | Likely vulnerable in most matchups |
| Over 5.00 | Struggling | Fade material; getting hit hard |
Pro Tip: Combine ERA with WHIP, strikeout rate, and recent performance for a more complete picture before making your bets.
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Related article: How to Calculate Batting Average
