Era Earned Run Average Calculator
Calculate era earned run average with our free tool. See your stats, compare against averages, and track progress over time.
Formula
ERA = (Earned Runs / Innings Pitched) x 9
ERA measures the average number of earned runs a pitcher surrenders per nine innings. It is calculated by dividing earned runs by total innings pitched, then multiplying by nine (a regulation game length). Lower ERA indicates better pitching performance.
Worked Examples
Example 1: Starting Pitcher Mid-Season
Problem: A starting pitcher has allowed 25 earned runs over 75 innings pitched in 12 starts, with 65 hits and 20 walks allowed.
Solution: ERA = (25 / 75) x 9 = 0.3333 x 9 = 3.00\nWHIP = (20 + 65) / 75 = 85 / 75 = 1.133\nHits per 9 = (65 / 75) x 9 = 7.80\nWalks per 9 = (20 / 75) x 9 = 2.40\nAvg IP per start = 75 / 12 = 6.25\nRating: Excellent / All-Star level
Result: ERA = 3.00 | WHIP = 1.133 | Rating: Excellent
Example 2: Relief Pitcher with Partial Innings
Problem: A reliever has 8 earned runs in 45.2 innings (45 innings plus 2 outs), with 35 hits and 15 walks.
Solution: Total IP = 45 + 2/3 = 45.667 innings\nERA = (8 / 45.667) x 9 = 0.1752 x 9 = 1.58\nWHIP = (15 + 35) / 45.667 = 50 / 45.667 = 1.095\nHits per 9 = (35 / 45.667) x 9 = 6.90\nWalks per 9 = (15 / 45.667) x 9 = 2.96\nRating: Elite / Cy Young level
Result: ERA = 1.58 | WHIP = 1.095 | Rating: Elite
Frequently Asked Questions
What is ERA and how is it calculated in baseball?
ERA (Earned Run Average) is the most widely used statistic for evaluating a pitcher's effectiveness. It represents the average number of earned runs a pitcher allows per nine innings pitched. The formula is ERA = (Earned Runs / Innings Pitched) x 9. Earned runs are runs that score without the benefit of errors or passed balls by the defense. For example, if a pitcher allows 30 earned runs over 100 innings, their ERA is (30/100) x 9 = 2.70. ERA has been the standard pitching metric since the early 1900s and remains central to pitcher evaluation, contract negotiations, and award voting such as the Cy Young Award. Lower ERA values indicate better pitching performance.
What is a good ERA in Major League Baseball?
ERA standards vary by era and league context, but general benchmarks for MLB are: below 2.00 is elite and historically exceptional, comparable to pitchers like Pedro Martinez or Bob Gibson. An ERA between 2.00 and 3.00 is excellent and typically represents All-Star caliber pitching. Between 3.00 and 3.50 is above average and indicates a solid number-two or number-three starter. An ERA of 3.50 to 4.00 is roughly league average. Between 4.00 and 4.50 is below average, and above 5.00 generally indicates a struggling pitcher. The league-average ERA fluctuates: in the steroid era it exceeded 4.50, while in recent years it has hovered around 4.00 to 4.25 due to increased home run rates and offensive strategies.
What is the difference between ERA and earned runs vs unearned runs?
The distinction between earned and unearned runs is fundamental to understanding ERA. An earned run is any run that scores through the pitcher's responsibility: hits, walks, hit batters, and balks. An unearned run scores due to defensive errors, passed balls, or catcher interference that extend an inning beyond what should have occurred. The official scorer must reconstruct what would have happened without the error to determine which runs are earned. For example, if a fielder drops a routine fly ball and the next batter hits a home run, both runs are typically unearned. This distinction means ERA specifically measures the pitcher's contribution to run prevention, isolating their performance from defensive quality behind them.
What is WHIP and how does it complement ERA?
WHIP (Walks plus Hits per Innings Pitched) measures how many baserunners a pitcher allows per inning. Calculated as (Walks + Hits) / Innings Pitched, it provides insight into a pitcher's ability to prevent batters from reaching base. While ERA shows run-prevention results, WHIP captures the process, as fewer baserunners generally lead to fewer runs. A WHIP below 1.00 is elite (meaning fewer than one baserunner per inning on average), 1.00 to 1.15 is excellent, 1.15 to 1.30 is above average, and above 1.40 indicates significant baserunner management issues. WHIP is less affected by luck and sequencing than ERA, making it a more stable predictor of future performance and a useful complementary statistic for comprehensive pitcher evaluation.
How are partial innings recorded and calculated in ERA?
In baseball, innings pitched are recorded using a fractional system where each out represents one-third of an inning. A pitcher who records one out in an inning is credited with 0.1 innings (displayed as such on stat sheets but calculated as 1/3), two outs equals 0.2 innings (2/3), and a complete inning is 1.0. So a stat line showing 6.2 innings means six complete innings plus two outs in the seventh, which equals 6 and 2/3 innings or 20/3 innings for calculation purposes. This precision matters for ERA accuracy. For example, a pitcher with 3 earned runs in 6.2 innings has an ERA of (3 / 6.667) x 9 = 4.05, not (3 / 6.2) x 9 = 4.35 which would be the incorrect calculation using the display format directly.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.