打席数是棒球运动中的一项统计数据，指一个打击手完成一次打击的次数。所谓完成一次打击数，包括被三振、保送、或将球击到界内、将球击成界外高飞球被接杀等等。有几种情形下，会有打者出场，但未完成打击而不能获得打席数：

打席数主要代表了一个打击者实际出场打击的次数，尤其牵涉到个人的打击率是否被认为有意义。 例如在中华职棒，打击率最高的球员平均一场需要有3.1以上的打席数，才能获得打击王的奖项。

In baseball statistics, a player is credited with a plate appearance (denoted by PA) each time he completes a turn batting. A player completes a turn batting when: he strikes out or is declared out before reaching first base; or he reaches first base safely or is awarded first base (by a base on balls, hit by pitch, or catcher's interference); or he hits a fair ball which causes a preceding runner to be put out for the third out before he himself is put out or reaches first base safely (see also left on base, fielder's choice, force play). In other words, a plate appearance ends when the batter is put out or becomes a runner. A very similar statistic, at bats, counts a subset of plate appearances that end under certain circumstances.