Baseball Glossary › Innings Pitched
Innings Pitched (IP)
Innings pitched (IP) measures how long a pitcher stays in the game, counted by outs. Each out recorded while he is pitching is one-third of an inning. Box scores write thirds as .1 and .2, so 6.1 IP means six and one-third innings and 6.2 means six and two-thirds. It is not a decimal.
Formula
Worked example (illustrative numbers): a starter records 17 outs.
17 / 3 = 5 innings with 2 outs left over, written 5.2 IP
For math such as ERA, use 5 2/3 = 5.667, not 5.2
Athletics example: Dennis Eckersley
Dennis Eckersley's career line lists 3285.2 innings pitched. The ".2" is not a decimal: it means 2 extra outs, so 3285 and 2/3 innings. See the full career line on the Dennis Eckersley player page.
Outs recorded = 3285 x 3 + 2 = 9,857
True innings = 9,857 / 3 = 3285.667
Career MLB totals from our player database (MLB Stats API).
What to Know
The Official Baseball Rules tell the scorer to count each putout as one-third of an inning. A starter replaced with one out in the sixth gets 5 1/3 innings; one replaced with nobody out in the sixth gets 5 innings. A pitcher who enters and is removed without recording an out gets no innings, even though he made an appearance.
Because .1 and .2 are thirds, adding innings needs care: 5.2 plus 1.1 is 7 innings, not 6.3. Convert to outs or true thirds before you calculate ERA, WHIP or strikeouts per nine innings.
Outs on pickoffs and caught stealings count toward IP, and a double play adds two-thirds of an inning. A batter reaching on an error adds nothing, because no out was made. Starters use innings as a sign of durability, which is also why the quality start requires at least six.
Frequently Asked Questions
What does IP mean in baseball?
IP stands for innings pitched. It counts how many innings a pitcher has worked, based on the outs recorded while he was on the mound. Three outs equal one inning.
What does 5.1 innings pitched mean?
It means five and one-third innings. The number after the dot is the count of extra outs, not a decimal. So 5.1 is 5 innings plus one out, and 5.2 is 5 innings plus two outs.
Why is there never a .3 in innings pitched?
Three outs complete an inning, so a third out turns the count into the next whole number. After 5.2, one more out makes it 6.0 innings pitched.
How do you convert innings pitched for ERA?
Change .1 to .333 and .2 to .667 before calculating. For example, 9.1 IP becomes 9.333 innings, and 3 earned runs over that span is an ERA of 2.89.
Does a pitcher get innings if he records no outs?
No. A pitcher who faces batters but is removed before any out is made is credited with zero innings pitched, though he still gets an appearance and can be charged with runs.
Do double plays and pickoffs count toward innings pitched?
Yes. Any out made while the pitcher is in the game counts, including pickoffs and caught stealings. A double play adds two outs, which is two-thirds of an inning.
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Sources
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