ERA Calculator
Work out a pitcher's earned run average and WHIP from earned runs, hits, walks and innings pitched, with innings typed the box-score way, 6.2 for 6⅔.
Result
Earned run average (ERA): 2.70
Innings are counted in thirds, one per out, so 6.2 in a box score means six and two-thirds innings, not 6.2.
- Walks plus hits per inning (WHIP)
- 1.05
- Innings as a decimal
- 6.6667
- Outs recorded
- 20
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Results are exact arithmetic on the numbers you enter, following the rule or formula the page names. Official records are kept by the league, federation or association concerned, and their figures and rulings control. Read the full disclaimer
How to use the ERA Calculator
- Enter the earned runs charged to the pitcher and the innings pitched, typed the way a box score shows them, 6.2 for six and two-thirds.
- Add hits and walks allowed if you want WHIP as well.
- Read the earned run average and WHIP to two decimal places, with the innings converted to outs so you can check them.
The formula
Rule 9.21(e) of the Official Baseball Rules scales earned runs to a nine-inning game:
ERA = 9 × earned runs ÷ innings pitchedWHIP = (hits + walks) ÷ innings pitchedinnings pitched = outs recorded ÷ 3The page counts outs first. 200.1 innings is 601 outs, 200⅓ innings, and every division is done on that exact figure, so no rounding of two-thirds to 0.67 creeps into the rate. Rounding to two decimal places happens only when the result is shown.
Reading box-score innings
Box scores use a point for thirds: 5.1, 5.2, then 6.0. There is no 6.3, because three outs make the next inning, and the page refuses one rather than guess. You can also type the innings as a fraction, 6 2/3, or a lone 2/3 for a reliever who got two outs.
What the rate does not include
Only earned runs count. The official scorer decides which runs would have scored without errors or passed balls, and those decisions are not something a formula can redo, so enter the earned runs as recorded.
With your numbers
- 6.2 innings = 20 outs = 6⅔ innings
- ERA = 9 × 2 ÷ 6⅔ = 2.70
- WHIP = (5 + 2) ÷ 6⅔ = 1.05
Quick reference
Innings are counted in thirds, one per out, so 6.2 in a box score means six and two-thirds innings, not 6.2.
| Example | Earned run average (ERA) |
|---|---|
| 2 earned runs in 6.2 innings | 2.70 |
| 3 earned runs in 9⅓ innings, the rule book example | 2.89 |
| A season: 60 in 200.1 innings, 170 hits, 50 walks | 2.70 |
| 1 earned run in a third of an inning | 27.00 |
| 0 earned runs in 0.2 innings, 1 hit | 0.00 |
| 3 earned runs in 7 innings, scaled to 7 | 3.00 |
Common questions about the ERA Calculator
- Why does 6.2 innings mean six and two-thirds?
- An inning has three outs, and a pitcher is credited with a third of an inning for each out recorded while pitching. Box scores write the thirds after a point, so .1 is one out and .2 is two. It is notation, not a decimal: 6.2 innings is 6.667, and treating it as 6.2 overstates an ERA.
- How is ERA calculated?
- Rule 9.21(e) multiplies the earned runs by 9 and divides by the innings pitched, fractions of an inning included. The rule book’s own example is 3 earned runs in 9⅓ innings, which is 27 ÷ 9⅓ = 2.89. The answer is the earned runs the pitcher would allow over nine innings at the same rate.
- What if a pitcher allowed runs without getting anyone out?
- With no outs there are no innings pitched, and dividing by zero has no answer, so the page does not give one. Record books show such an ERA as infinite.
- Is WHIP in the official rules?
- No. The rules define ERA but not WHIP, which MLB describes as walks plus hits divided by innings pitched. Hit batters, errors and batters who reach on a fielder’s choice do not count in it.
- Can I work out ERA for seven-inning games?
- Yes. The rule uses 9, and the page does too unless you change the regulation game length under More options. Some leagues that play seven innings scale by 7; check which your league uses.