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ERA Calculator

An earned run average is one division, and the number to divide by is the part a calculator can quietly get wrong. Innings pitched are written in thirds: 6.1 is six innings and one out, which is 19 outs, not 6.1 of an inning, and reading it as a decimal moves three earned runs from 4.26 to 4.43. This page converts the entry into outs first, shows that out count in the readout beside the answer, and takes the line either way round, so a relief outing counted in outs needs no conversion by hand. The regulation length is a switch, nine innings for baseball and seven for softball, and the one it used is printed on the stage with the result. The line it opens on is 12 earned runs in 32.0 innings, which is 3.38.

ERA3.3812 earned runs · 32.0 innings (96 outs) · 9 inning scaleNine innings is baseball's regulation length.
ERA
3.38
Earned runs
Innings
Outs
96
Entered as
Regulation length
  • 12 ER, 32.0 innings9 inning scale
    3.38
  • 32.0 inningsnotation read
    96 outs, ERA 3.38
  • 7 inning scalesame line
    2.63

12 earned runs divided by 32.000 innings pitched, times 9 innings of regulation, is 3.375, shown as 3.38. Innings pitched is 96 outs divided by 3.

The exact figure is 3.375; the page shows two decimals, the way a box score does.

Earned runs per inning pitched: 0.375, before the 9 inning scale.

Accuracy. Exact arithmetic: earned runs divided by innings pitched, times the regulation length you choose. Baseball notation is read the way it is written, so 32.2 means 32 innings and 2 outs, which is 98 outs, and the page shows the converted outs so you can check it.

How to write the innings

Innings go in the notation a box score prints: 6 or 6.0 for six full innings, 6.1 for six and one out, 6.2 for six and two outs. Thirds written as fractions read the same way, so 6 1/3 is 6.1. A figure past .2, such as 6.3 or 6.75, is refused rather than guessed at, because it is a different convention: switch Entered as to Outs and give the out count instead. The Outs cell always shows what the innings came to, and the regulation length switches between nine innings for baseball and seven for softball.

Common questions

How do you calculate ERA?
Earned runs divided by innings pitched, times the length of a regulation game. The page opens on 12 earned runs in 32.0 innings, which is 96 outs: 12 divided by 32 innings is 0.375 earned runs an inning, and times nine innings that is 3.375, shown as 3.38. Two decimals are what a box score prints, so the page names the undivided figure underneath whenever the rounding hides something.
What does 6.1 innings mean?
Six innings and one out, which is 19 outs. The digit after the point counts outs rather than tenths, so .1 is one out and .2 is two, and there is no .3 because three outs end the inning. The difference is not cosmetic: three earned runs in 6.1 innings is 4.26, while treating 6.1 as a decimal gives 4.43. That is why this page shows the out count next to the average.
How do you work out ERA in softball, over seven innings?
Set the regulation length to 7 innings and the same line is scaled to a seven inning game. The 12 earned runs in 32.0 innings that come to 3.38 over nine innings come to 2.63 over seven, because the scale is the only thing that changed: the earned runs and the 96 outs are untouched. Nine innings is the baseball default, and the page prints which length it used on the stage beside the result.
Can I enter outs instead of innings?
Yes. Set Entered as to Outs and give the out count, so 19 rather than 6.1, which suits a partial outing you counted in outs. The page converts it back and shows 6.1 in the Innings cell, so both readings are on screen together, and switching between the two carries the figure across instead of clearing it. Thirds written as fractions read too, so 6 1/3 is the same as 6.1.
What happens if I type 6.5 innings?
It is refused, and the message says what to write instead. Innings notation only uses .0, .1 and .2, for no outs, one out and two outs, so 6.5 is not a figure this page will guess at: reading it as six and a half innings would be a different convention, and nothing is rounded or cut behind your back. Decimal thirds are caught the same way, so 6.33 and 6.67 are pointed back at 6.1 and 6.2.
What counts as an earned run?
A run that scored without the help of an error or a passed ball, and it is the official scorer who decides which runs those are. This page takes your figure for it. It divides the earned runs you give it by the innings you give it, and it cannot know which runs the scorer charged to the pitcher, so the split between earned and unearned has to come from the box score.
What is a good ERA?
This page does not grade the number, because what counts as good depends on the level, the park and the season, none of which a calculator knows. What the figure means is fixed: it is the earned runs given up per regulation game, so a lower ERA is fewer earned runs over the same innings. A 3.38 says the 12 earned runs and 96 outs entered work out at 3.38 earned runs per nine innings.
Is anything uploaded?
No. The arithmetic runs in your browser, nothing is sent anywhere and no figure you type reaches a server. The line you last worked on is remembered in your own browser storage so the page opens where you left it, and clearing your browsing data clears it. Copy puts the ERA and the line it came from on the clipboard as plain text, ready for a message or a scorebook note.

Exact arithmetic: earned runs divided by innings pitched, times the regulation length you choose. Baseball notation is read the way it is written, so 32.2 means 32 innings and 2 outs, which is 98 outs, and the page shows the converted outs so you can check it.