ERA Calculator With WHIP and K/9
ERA (earned run average) is earned runs times 9, divided by innings pitched. Enter his pitching line below to get ERA, WHIP, strikeouts and walks per nine, strike percentage, and pitches per inning. It works for 6-inning youth games, 7-inning high school games, and the standard 9-inning scale, and it reads innings the way a scorebook writes them (5.2 means 5 and 2/3).
How to calculate ERA (formula and example)
The ERA formula is earned runs x 9 / innings pitched. ERA (earned run average) is the number of earned runs a pitcher allows per nine innings. Multiply his earned runs by 9, then divide by his innings pitched. A pitcher who allows 3 earned runs in 5 2/3 innings has an ERA of 4.76. The table shows every formula this calculator uses, worked out for that same line: 5.2 innings, 3 earned runs, 6 hits, 2 walks, 7 strikeouts, 54 strikes on 85 pitches, and 14 first-pitch strikes to 24 batters.
| Stat | Formula | Example |
|---|---|---|
| ERA (9 innings) | Earned runs x 9 / innings pitched | 4.76 |
| ERA (7 innings) | Earned runs x 7 / innings pitched | 3.71 |
| ERA (6 innings) | Earned runs x 6 / innings pitched | 3.18 |
| WHIP | (Walks + hits) / innings pitched (hit batters and errors don't count) | 1.41 |
| K/9 | Strikeouts x 9 / innings pitched | 11.1 |
| BB/9 | Walks x 9 / innings pitched | 3.2 |
| H/9 | Hits x 9 / innings pitched | 9.5 |
| K/BB | Strikeouts / walks | 3.50 |
| Strike % | Strikes / total pitches x 100 | 63.5% |
| First-pitch strike % | First-pitch strikes / batters faced x 100 | 58.3% |
| Pitches per inning | Total pitches / innings pitched | 15.0 |
How to calculate innings pitched (5.1 and 5.2)
Every out is a third of an inning, so a scorebook writes 5 1/3 innings as 5.1 and 5 2/3 innings as 5.2. Those aren't decimals. In the math, 5.2 innings is 5.67 innings, not 5.2, and treating it like a decimal is the most common reason a hand-figured ERA comes out wrong. This calculator converts it for you. A pitcher who leaves before getting an out in an inning gets no innings credit for it, but the runs charged to him still count.
| Scorebook | Outs | Innings in the math |
|---|---|---|
| 0.2 | 2 | 0.67 |
| 5.0 | 15 | 5.00 |
| 5.1 | 16 | 5.33 |
| 5.2 | 17 | 5.67 |
| 6.0 | 18 | 6.00 |
Season ERA: add it up, don't average it
To figure ERA for a season, add up all his earned runs and all his innings first, then run the formula once on the totals. Don't average his game-by-game ERAs. Averaging counts a one-inning outing the same as a six-inning start, and that skews the number. Say he allows 3 earned runs in 1 inning one game (a 27.00 ERA) and throws 6 scoreless innings the next (0.00). The average of those two is 13.50, but his real ERA is 3 earned runs in 7 innings: 3.86. Total innings by outs, not decimals, so 5.2 plus 4.1 is 10 innings, not 9.3. Enter the season totals above and the calculator handles the rest.
Earned runs vs. unearned runs
Only earned runs go into ERA. An earned run is one the pitcher is held responsible for under the scoring rules. When a runner reaches base on an error or a passed ball, or scores because of one, the run is usually unearned and stays out of his ERA. A run that scores on a wild pitch is earned, because a wild pitch is charged to the pitcher. When an error keeps an inning alive, the scorer replays the inning as if the play had been made, and any run that wouldn't have scored is unearned. It's the scorekeeper's call, so use the earned runs from his scorebook, not the runs on the scoreboard.
ERA for 7-inning high school and 6-inning games
The standard ERA scale is nine innings, the length of a college or pro game, and college and pro rules figure ERA on nine innings. High school games are seven innings and Little League Majors and younger play six, so some teams and stat services figure ERA per seven or six innings instead. Either way works, as long as you compare pitchers on the same scale. On the same pitching line, a 7-inning ERA is always 7/9 of the 9-inning number and a 6-inning ERA is 2/3 of it, so a high school ERA reads lower than the same outing on the standard scale. Pick his game length and this calculator shows that ERA next to the standard nine-inning number.
What WHIP, K/9 and BB/9 tell you
ERA gets the headlines, but the other numbers say more about how he's pitching. WHIP is walks plus hits per inning, so it's roughly how many runners he puts on base each inning from walks and hits. BB/9 is walks per nine innings, the number to watch when he's fighting the strike zone. K/9 counts strikeouts per nine, and K/BB shows how many strikeouts he gets for every walk. Pitches per inning shows how efficient he is. Long innings run up his pitch count, and the pitch count is what ends his outing. Watch the trend over several games. A dropping BB/9 or a rising strike percentage usually shows up before his ERA moves.
Strike percentage and first-pitch strikes
Strike percentage counts every pitch that isn't a ball: called strikes, swinging strikes, foul balls, and balls put in play. That's how pitch counts are kept, even though a ball put in play isn't a strike in the rulebook. First-pitch strike percentage is the share of batters who saw strike one, and a first pitch put in play counts as a strike. Both show whether he's working ahead in the count, and they move faster than ERA does, so they show progress sooner.
What is a good ERA?
There isn't one number that makes an ERA good at every level. Game length changes the math, and so do the hitters he faces and how the scorekeeper calls hits and errors. The scale matters most. The same 3 earned runs in 5 2/3 innings is a 3.71 ERA on a 7-inning scale and 4.76 on the 9-inning scale, so a high school ERA and a college ERA aren't the same yardstick. Compare pitchers only on the same scale and at the same level, and compare him mostly to his own numbers from earlier in the season. ERA also moves slowly. Strike percentage, first-pitch strikes and walks per nine change sooner, so they show progress first.
What the numbers can't tell you
Stats describe results: runs, walks, strikeouts, long innings. They can't show why a pitcher walks the bottom of the order or runs out of gas by the fourth inning, and those answers are usually in the delivery. Track his numbers game to game against his own, not against the kid on Instagram. When the same problem keeps showing up, film a pitch from the side and look at the delivery.
Common questions
How do you calculate ERA?
Multiply earned runs by 9 and divide by innings pitched. For 3 earned runs in 5 2/3 innings: 3 x 9 / 5.67 = 4.76.
What does 5.2 innings pitched mean?
Five innings plus two outs, or 5 2/3 innings. Scorebooks count outs in thirds, so .1 means one out and .2 means two outs into the next inning. There is no .3, because three outs completes the inning.
How do you calculate ERA for a 7-inning high school game?
Use 7 instead of 9: earned runs x 7 / innings pitched. The same 3 earned runs in 5 2/3 innings is a 3.71 ERA on a 7-inning scale and 4.76 on the standard 9-inning scale.
How do you calculate ERA for a whole season?
Add up all his earned runs and all his innings for the season, then use the formula once: earned runs x 9 / innings pitched. Total the innings by outs, so 5.2 plus 4.1 is 10 innings. Don't average his single-game ERAs, because that counts a one-inning outing the same as a full start.
Do unearned runs count in ERA?
No. ERA counts only earned runs. A run that scores because of an error or a passed ball is usually unearned and stays out of his ERA, while a run that scores on a wild pitch is earned. Unearned runs still count on the scoreboard and in his runs allowed, just not in his ERA.
What is a good ERA for a high school pitcher?
There's no single cutoff. High school games are seven innings, so many teams figure ERA on a 7-inning scale, which reads lower than the same line on the 9-inning scale used in college and pro baseball. Compare pitchers on the same scale and at the same level, and judge him mostly against his own numbers. Walks per nine and strike percentage show progress sooner than ERA does.
Can a pitcher have an infinite ERA?
Yes. If he allows an earned run before recording an out, he has earned runs and zero innings pitched. You can't divide by zero, so his ERA is infinite. It stays that way only until he gets outs. Once he records an out, the formula gives a normal number again, though one outing like that can keep a short-season ERA high for a while.
How do you calculate WHIP?
Add walks and hits, then divide by innings pitched. 2 walks and 6 hits in 5 2/3 innings is a WHIP of 1.41, meaning about 1.4 base runners per inning from walks and hits. Hit batters and runners who reach on errors don't count.
What counts as a strike for strike percentage?
Every pitch that isn't a ball: called strikes, swinging strikes, foul balls, and balls hit into play. Divide strikes by total pitches and multiply by 100.
Keep reading
More free tools
Last updated October 17, 2026
Walks and long innings usually trace back to the delivery.
A coach-reviewed video evaluation shows what in his mechanics is costing him strikes and what to fix first. Free, from one short phone video.
Get His Free Evaluation