Slugging percentage is a player's total bases divided by at bats. Total bases are calculated by 1 total base for a single, 2 for a double, 3 for a triple, 4 for a homer. What the slugging percentage tells you is the average number of bases accrued by the player in each at bat. IE: A slugging percentage of .500 indicates that the player averages half a base per at bat. The highest possible slugging percentage is 4.000, which would mean the player hits a homer in every at bat.