ERA Calculator

ERA Calculator

Calculate Earned Run Average (ERA) for baseball pitchers and compare it with rough context-dependent reference bands.

Last updated: March 2026 | By Patchworkr Team

Pitcher Statistics

Earned Run Average

3.75

Informal context: Above Average

Informal Earned Run Average Guide

ERARatingPerformanceContext (MLB)
≤2.00Elite (Cy Young)Dominant pitcherHall of fame trajectory
2.01-3.00Excellent (Ace)Staff aceMost valuable pitcher
3.01-4.00GoodQuality starterAbove league average
4.01-4.50AverageLeague average~4.20 MLB median
4.51-5.00Below AverageSpot starter levelBelow average
>5.00PoorStrugglingLikely DFA candidate

Note: These labels are rough MLB-oriented context only. ERA varies by league, era, park, role, and sample size. It does not include unearned runs charged to the pitcher.

What is Earned Run Average?

Earned Run Average (ERA) is the mean of earned runs given up by a pitcher per nine innings pitched. It is the most widely used statistic for evaluating pitcher performance in baseball and softball. ERA provides a standardized way to compare pitchers regardless of how many innings they've pitched.

The statistic only counts "earned" runs—those that resulted from hits, walks, or hit batters, excluding runs scored due to defensive errors. This isolates the pitcher's performance from defensive mistakes made by their teammates. A lower ERA indicates better pitching performance, with elite pitchers typically maintaining ERAs below 3.00 throughout a season.

ERA has been tracked since the early 1900s and remains the gold standard for pitcher evaluation, despite newer metrics like FIP (Fielding Independent Pitching) and xFIP that attempt to isolate pitcher skill even further. The Cy Young Award, given annually to the best pitchers in each league, heavily weights ERA in voting considerations.

How to Calculate ERA

The ERA Formula

ERA = (Earned Runs × 9) / Innings Pitched

The number 9 represents a standard game length (9 innings). This normalizes the statistic regardless of how many innings a pitcher actually threw.

Earned vs. Unearned Runs

Understanding which runs count toward ERA:

Earned Runs: Runs scored via hits, walks, hit batters, balks, wild pitches, or passed balls
Unearned Runs: Runs that scored because of fielding errors or defensive interference

ERA Benchmarks

Under 2.00: Elite/historic season
2.00-3.00: Excellent/Cy Young contender
3.00-4.00: Above average/solid starter
4.00-5.00: Average/back-end rotation
Over 5.00: Below average/needs improvement

Example Calculation

Calculate ERA for a starting pitcher:

Given:
Earned Runs: 27
Innings Pitched: 85.1 (85 ⅓ innings)
Step 1:
Convert innings to decimal:
85.1 = 85 + (1/3) = 85.333 innings
Step 2:
Apply ERA formula:
ERA = (27 × 9) / 85.333
ERA = 243 / 85.333
ERA = 2.85
Result:
ERA: 2.85

Rating: Excellent — ace level pitcher

Frequently Asked Questions

What is a good ERA in baseball?

An ERA below 4.00 is generally considered good, with elite pitchers maintaining ERAs below 3.00. The league average ERA typically ranges from 4.00 to 4.50 depending on the era and ballpark factors.

How are partial innings recorded?

Each out is worth ⅓ of an inning. So 6.1 IP means 6 innings plus 1 out (6⅓ innings = 6.333). 6.2 IP means 6 innings plus 2 outs (6⅔ innings = 6.667).

Do inherited runners count in ERA?

If you allow an inherited runner to score, it counts against the previous pitcher's ERA, not yours. However, if you pitch poorly and allow your own runners to score later, those count against you.

Does ERA account for ballpark factors?

No, standard ERA does not adjust for ballpark dimensions or environmental factors. ERA+ is an adjusted version that normalizes for ballpark and league, where 100 is average and higher is better.

What's the difference between ERA and RA?

ERA counts only earned runs, while RA (Run Average) includes all runs scored, even those caused by defensive errors. RA gives a complete picture of runs allowed regardless of how they scored.

Can ERA be negative or zero?

ERA can be exactly 0.00 if no earned runs are allowed (perfect record). It cannot be negative. Pitchers with 0.00 ERA through limited innings have allowed no earned runs.

How does ERA apply to relief pitchers?

ERA works the same way but is often higher for relievers due to smaller sample sizes and high-leverage situations. Elite closers typically maintain ERAs around 2.00-3.00, while middle relievers average 3.50-4.50.

What's the lowest ERA in MLB history?

Tim Keefe holds the record with 0.86 ERA in 1880. In the modern era (post-1900), Dutch Leonard's 0.96 ERA in 1914 stands as the lowest. Pedro Martinez's 1.74 ERA in 2000 is legendary.

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