Per-minute ratings evaluate a player’s performance more accurately than his per-game averages.
The common notation for per-minute ratings is using per 36-minute, or per 40-minute stats.
Per-minute ratings are calculated by taking the player's total in any category (points, rebounds, assists, etc.) divided by total minutes played.
For example; if a player gets 24 minutes per game, and his points average per game is 12, he’d score (36*12)/24=18 points if he’d play 36 minutes.