Free era calculator
Calculate any pitcher's ERA in two seconds. Enter earned runs and innings pitched — using baseball's .1/.2 notation, which this calculator converts correctly (6.2 IP = 6⅔ innings, not 6.2) — and the ERA calculator returns the earned run average, a good-ERA rating, and optional WHIP, with the full rating scale, updated live, as you type.
On this page14 sections
| ERA range | Rating |
|---|---|
| Below 2.00 | Excellent (elite) |
| 2.00 – 2.99 | Great |
| 3.00 – 3.99 | Good |
| 4.00 – 4.99 | Average |
| 5.00 and above | Poor |
ERA = (earned runs ÷ innings pitched) × 9. Innings use baseball .1/.2 notation (.1 = ⅓, .2 = ⅔). See how partial innings work
Results are estimates. Consult a professional.
What is earned run average (ERA)?
Earned run average (ERA) is the headline statistic for a baseball pitcher: the average number of earned runs they give up per nine innings — the length of a standard game. A lower ERA is better, and the number this ERA calculator returns the moment you enter earned runs and innings pitched is the same figure printed on every box score, baseball card, and broadcast graphic.
The word that does the heavy lifting is earned. An earned run is a run that scores through the pitcher's own doing — hits, walks, home runs. A run that only scores because of a fielding error or a passed ball is an unearned run and is left out of ERA, because it was not the pitcher's fault. ERA is built to isolate how well the pitcher themselves prevented runs.
How to calculate ERA
ERA takes the earned runs a pitcher allowed, divides by how many innings they pitched to get earned runs per inning, then multiplies by nine to scale it to a full game. Three steps:
- Divide earned runs by innings pitched. This is the pitcher's earned runs per single inning.
- Multiply by 9. A regulation game is nine innings, so this scales the rate to a full game.
- Read the result. The number is earned runs per nine innings — the ERA. The calculator above does all three live as you type.
The multiply-by-nine step is what makes ERAs comparable. A reliever who throws 60 innings and a starter who throws 200 can't be compared on raw runs allowed — but per nine innings, they're on the same scale. That's why ERA is quoted as a single number like 3.60 regardless of how much the pitcher actually worked.
Innings pitched and partial innings (.1 and .2)
The one place ERA trips people up is innings pitched (IP). Baseball writes partial innings in a notation where the decimal is a count of outs, not a fraction of ten. Each inning is three outs, so each out is one-third of an inning:
| IP notation | Means | True innings |
|---|---|---|
| 6.0 | 6 full innings | 6 |
| 6.1 | 6 innings + 1 out | 6 ⅓ ≈ 6.333 |
| 6.2 | 6 innings + 2 outs | 6 ⅔ ≈ 6.667 |
| 7.0 | back to a full inning (3 outs) | 7 |
The decimal in IP only ever goes .0, .1, or .2 — there is no .3 through .9, because the third out completes the inning and rolls it over.
Worked the other way: a pitcher who records 20 outs has pitched 20 ÷ 3 = 6 innings and 2 outs, written 6.2 IP. The conversion (outs ÷ 3) is the whole reason a good ERA calculator beats doing it by hand.
A worked example using the ERA calculator
Marcus pitches into the 7th inning and is pulled after recording two outs, having given up 2 earned runs. His line reads 6.2 IP. Here is exactly how the calculator turns that into an ERA.
Step 1 — Convert innings pitched to true innings
6.2 IP means 6 full innings plus 2 outs. Two outs is two-thirds of an inning, so the true figure is 6 + 2/3 = 6.667 innings, not 6.2. This is the step a basic calculator gets wrong.
Step 2 — Divide earned runs by true innings
2 earned runs ÷ 6.667 innings = 0.30 earned runs per inning.
Step 3 — Multiply by nine
0.30 × 9 = 2.70. (For comparison, the wrong way — 2 ÷ 6.2 × 9 — gives 2.90, a tenth of a run too high.)
What is a good ERA?
A good ERA depends on the era of baseball and the pitcher's role, but at the Major League level the rule of thumb is simple: under 3.00 is excellent to elite, around 4.00 is league average, and over 5.00 is poor. The bands below are the ones this calculator uses to label your result.
| ERA range | Rating | What it means |
|---|---|---|
| Below 2.00 | Excellent (elite) | Ace / Cy Young territory — among the very best in the league. |
| 2.00 – 2.99 | Great | A genuine front-line starter or lockdown reliever. |
| 3.00 – 3.99 | Good | A solid, reliable, above-average pitcher. |
| 4.00 – 4.99 | Average | Roughly league-average run prevention — a back-of-rotation arm. |
| 5.00 and above | Poor | Below replacement level over a full season; tough to keep in the rotation. |
Bands used by this calculator. Standards shift over time and by role — relievers and closers are generally held to a lower (better) ERA than starters.
Context matters. League-average ERA drifts up and down across decades with the rules and the ball — it sat near 4.50 in the high-offense early 2000s and closer to 3.00 in the pitching-dominated 1960s. A 3.50 ERA is good today; it would have been merely ordinary in 1968. Judge a pitcher against their own league and season, not a fixed number.
ERA vs WHIP vs FIP
ERA is the most familiar pitching stat, but it is not the only one — and it has a known blind spot. ERA depends on the defense behind the pitcher and on the timing of when runners score, so two pitchers with identical skill can post different ERAs through luck. Two companion stats round out the picture.
WHIP — baserunners allowed
WHIP (walks plus hits per inning pitched) measures how many baserunners a pitcher allows, regardless of whether they score: WHIP = (walks + hits) ÷ innings pitched. A WHIP under 1.00 is elite, around 1.30 is average, and over 1.50 is poor. Because it ignores whether runners come around to score, WHIP often exposes a pitcher who has a deceptively low ERA — this calculator computes it for you if you enter walks and hits.
FIP — what the pitcher alone controls
FIP (Fielding Independent Pitching) strips out the defense entirely and is built only from outcomes a pitcher controls by themselves — strikeouts, walks, hit-by-pitches, and home runs. It is scaled to look like ERA (the league average is set around 3.10–3.20 with a constant), so a FIP of 3.50 reads like a 3.50 ERA. Because it removes defensive and sequencing luck, FIP is generally a better predictor of a pitcher's future ERA than their current ERA is.
| Stat | Measures | Lower is better? |
|---|---|---|
| ERA | Earned runs allowed per 9 innings | Yes |
| WHIP | Walks + hits (baserunners) per inning | Yes |
| FIP | Strikeouts, walks, HBP, HR — defense-independent, on an ERA scale | Yes |
ERA tells you what happened; WHIP tells you how many runners got on; FIP estimates what the pitcher alone deserved.
ERA across baseball history
ERA has been tracked since the early 20th century, and the record book shows just how much the game's run environment has shifted. The lowest single-season ERA of the modern era belongs to Bob Gibson, whose 1.12 in 1968 was so dominant — alongside a league-wide pitching surge — that MLB lowered the mound the following season to give hitters a chance.
| Milestone | Pitcher | ERA |
|---|---|---|
| Lowest modern single-season ERA (1968) | Bob Gibson | 1.12 |
| Lowest career ERA, dead-ball era | Ed Walsh (1904–1917) | 1.82 |
| Lowest career ERA, live-ball era | Mariano Rivera (1995–2013) | 2.21 |
| Typical MLB league-average ERA | League (varies by season) | ≈ 3.9–4.5 |
Figures from Baseball-Reference and the Baseball Hall of Fame. "Dead-ball" and "live-ball" eras are split by the 1920 rule and equipment changes that boosted offense.
The takeaway for reading any ERA: the same number means different things in different eras. A sub-2.00 ERA is era-defining in any decade, but the line between "good" and "average" moves with the league's overall scoring.
Common ERA questions
What is a good ERA in baseball?
At the MLB level, an ERA under 2.00 is elite, under 3.00 is excellent, and under 4.00 is above average. Around 4.00 to 4.50 is roughly league average, and over 5.00 is poor for a regular pitcher. Relievers are generally held to a slightly lower (better) standard than starters.
How do you calculate ERA?
Divide the earned runs allowed by the innings pitched, then multiply by nine. For example, 72 earned runs over 180 innings is (72 ÷ 180) × 9 = 3.60. Only earned runs count — runs that scored on a fielding error or passed ball are excluded.
What does 6.2 innings pitched mean?
It means 6 full innings plus 2 outs — that is, 6⅔ innings, or about 6.667. The decimal in innings pitched counts outs, not tenths: .1 is one out (⅓) and .2 is two outs (⅔). The third out completes the inning, so there is no .3.
What's the difference between ERA and WHIP?
ERA measures earned runs allowed per nine innings; WHIP measures how many baserunners (walks plus hits) a pitcher allows per inning. A pitcher can have a low ERA but a high WHIP if runners get stranded — which often signals trouble ahead. Used together they give a fuller picture than either alone.
How this calculator works and sources
This ERA calculator applies the standard formula (earned runs ÷ innings pitched) × 9 exactly, converting the .1/.2 innings-pitched notation into true thirds of an inning before dividing. The optional WHIP figure uses (walks + hits) ÷ innings pitched on the same converted innings. All maths runs in your browser — nothing you enter is sent anywhere — and the formulas, rating bands, and historical figures are standard, well-documented baseball references.
MLB.com — Earned Run Average (ERA) glossary.Baseball-Reference — Earned Run Average glossary.Frequently asked questions about the free era calculator
About this ERA calculator
This ERA calculator runs entirely in your browser. The figures you enter never leave your device — nothing is sent to a server, logged, or shared. It applies the standard formula (earned runs ÷ innings pitched × 9), converting baseball's .1/.2 innings notation to true thirds of an inning first, and updates instantly on every change.
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