Innings pitched
Rank Player Year Team Innings pitched
1 Ed Walsh 1908 Chicago White Sox 464
2 Jack Chesbro 1904 New York Highlanders ​ 454 ⁄ 3
3 Joe McGinnity 1903 New York Giants 434
4 Ed Walsh 1907 Chicago White Sox ​ 422 ⁄ 3
5 Vic Willis 1902 Boston Beaneaters 410
6 Joe McGinnity 1904 New York Giants 408
7 Ed Walsh 1912 Chicago White Sox 393
8 Dave Davenport 1915 St. Louis Terriers ​ 392 ⁄ 3
9 Christy Mathewson 1908 New York Giants ​ 390 ⁄ 3
10 Jack Powell 1904 New York Highlanders ​ 390 ⁄ 3
Records -- Single season leaders
In baseball, innings pitched (IP) are the number of innings a pitcher has completed, measured by the number of batters and baserunners that are put out while the pitcher is on the pitching mound in a game. Three outs made is equal to one inning pitched. One out counts as one-third of an inning, and two outs counts as two-thirds of an inning. Sometimes, the statistic is written 34.1, 72.2, or 91.0, for example, to represent ​34 1⁄3 innings, ​72 2⁄3 innings, and 91 innings exactly, respectively. Runners left on base by a pitcher are not counted in determining innings pitched. It is possible for a pitcher to enter a game, give up several hits and possibly even several runs, and be removed before achieving any outs, thereby recording a total of zero innings pitched. Alternatively, it is possible for a pitcher to enter a situation where there are two runners on base and no outs. He'll throw one pitch which will result in a triple play, and for that one pitch he'll be credited with a full inning pitched.