Baseball Stats CalculatorERA Calculator
Enter earned runs and innings pitched. Type innings the box score way: 6.1 means 6 and 1/3, and 6.2 means 6 and 2/3.
Use .1 for one out and .2 for two outs.
Earned run average
2.89
- Innings as a number
- Outs recorded
- Per 9 innings
- Per 7 innings
By the Baseball Stats Calculator team · Formulas checked against Official Baseball Rules 9.21 · Last updated October 21, 2026 · How we check our math
How do you calculate ERA?
Multiply earned runs by 9. Then divide by innings pitched. Count each out as one third of an inning, so 6.1 innings is 6.333, not 6.1. For example, 3 earned runs in 9 1/3 innings gives 27 ÷ 9.333 = 2.89. This is the example in Rule 9.21(e) of the Official Baseball Rules.
ERA = (Earned runs × Innings in a game) ÷ Innings pitched
The rule book uses 9, the length of a pro game. The MLB.com glossary gives the same formula. For shorter games, swap 9 for the number of innings your games last.
Why the thirds matter
Rule 9.02(c) tells the scorer to count each putout as 1/3 of an inning. The box score then writes 1/3 as .1 and 2/3 as .2. That is a short way to write it, not a real decimal. If you put 6.1 into a normal calculator, you get the wrong answer.
| Box score | Means | Outs | Use in math |
|---|---|---|---|
| 5.0 | 5 innings | 15 | 5.000 |
| 5.1 | 5 1/3 innings | 16 | 5.333 |
| 5.2 | 5 2/3 innings | 17 | 5.667 |
| 0.1 | 1 out | 1 | 0.333 |
To add innings from several games, add the outs, then divide by 3. For example, 5.1 plus 3.2 is 16 plus 11 outs. That makes 27 outs, or 9.0 innings. The stat sheet does this for a whole staff.
Worked examples
Pro or college, 9 innings
A starter allows 2 earned runs in 6.1 innings. That is 19 outs, or 6.333 innings. ERA is 2 × 9 ÷ 6.333 = 2.84. If you typed 6.1 as a decimal, you would get 2.95, which is wrong.
High school or softball, 7 innings
A pitcher allows 10 earned runs in 35 innings. On a 7 inning base, ERA is 10 × 7 ÷ 35 = 2.00. On a 9 inning base, the same line is 2.57.
Little League, 6 innings
A pitcher allows 4 earned runs in 12 innings. On a 6 inning base, ERA is 4 × 6 ÷ 12 = 2.00.
Which game length should you pick?
Pick the length of a full game in your league. MLB and college games are 9 innings. NFHS high school games end after 7 innings under Rule 4-2-2. Little League lets local leagues set 6 inning games. Use 9 if you want to compare with pro or college numbers.
Sources: NFHS baseball rules and Little League Regulation VII.
What is a good ERA?
Lower is better. In MLB, the league ERA was 4.15 in 2025, 4.07 in 2024 and 4.33 in 2023, per Baseball-Reference. So an ERA under 4.00 was better than the league as a whole in each of those seasons. Youth and high school numbers vary a lot by league.
| Season | League ERA |
|---|---|
| 2025 | 4.15 |
| 2024 | 4.07 |
| 2023 | 4.33 |
Source: Baseball-Reference year by year pitching averages. No governing body for high school, college or Little League publishes a target ERA. The fairest test is to compare a pitcher with others in the same league and season.
Rounding
ERA is shown to two decimal places. This page rounds to the nearest hundredth, so 2.8929 shows as 2.89.
Related tools
Frequently asked questions
What does 6.1 innings pitched mean?
It means 6 full innings plus 1 out, or 6 and 1/3 innings. Each out is one third of an inning. A box score writes 6 1/3 as 6.1 and 6 2/3 as 6.2. You never see 6.3, because the third out makes it 7.0.
Do unearned runs count in ERA?
No. Only earned runs count. A run is unearned when it scores because of an error or a passed ball, as the MLB.com glossary explains. The official scorer decides which runs are earned.
Can ERA be higher than 27?
Yes. If a pitcher gives up earned runs and gets no outs, the ERA cannot be shown, since you would divide by zero. One earned run in one third of an inning is a 27.00 ERA in a 9 inning game.
Should I use 7 innings for high school ERA?
Many coaches use 7 because NFHS games last 7 innings. This gives runs per full game. Most stat services and college scouts use 9 so numbers compare across levels. Say which base you used when you share it.
How many decimal places does ERA use?
Two. MLB.com and the rule book example both show ERA to two places, such as 2.89. This page rounds the same way.
References
- Official Baseball Rules 2025 (PDF), Rules 9.02, 9.21 and 9.22, Major League Baseball
- Earned Run Average (ERA), MLB.com Glossary
- Innings Pitched (IP), MLB.com Glossary
- Major League Pitching Year by Year Averages, Baseball-Reference
- Baseball Rules, Rule 4-2-2 Ending a Regulation Game, NFHS
- Regulation VII: Making a Regular Season Schedule, Little League