Slugging percentage is a baseball statistic that measures the batting productivity of a hitter. It represents the total number of bases a player records per at-bat. Unlike batting average, slugging percentage gives more weight to extra-base hits such as doubles and home runs, relative to singles. Plate appearances resulting in walks, hit-by-pitches, catchers interference, and sacrifice bunts or flies are specifically excluded from this calculation, as such an appearance is not counted as an at-bat. The formula for slugging percentage is: (1B + 2Bx2 + 3Bx3 + HRx4)/AB, where AB is the number of at-bats.

Slugging percentage is a good tool for evaluating a players power, as it recognizes that not all hits are the same. A player who hits 45 home runs will come away with a pretty strong slugging percentage regardless of whether he hits .200 or strikes out often. Slugging percentage can also be applied as an evaluative tool for pitchers, although this is done less frequently. In such cases, it is referred to as slugging-percentage against.

A slugging percentage is always expressed as a decimal to three decimal places, and is generally spoken as if multiplied by 1000. For example, a slugging percentage of .589 would be spoken as "five eighty nine," and one of 1.127 would be spoken as "eleven twenty seven". The maximum numerically possible slugging percentage is 4.000.

Regarding what a good slugging percentage is, it depends on the context. In general, a slugging percentage above .500 is considered good, while a slugging percentage above .600 is considered outstanding, and a slugging percentage above .700 is considered elite.