This is how I understand it, please correct me if I'm wrong in any fashion Basically if it's 5 on 5 and each team gets called for one penalty a piece, it'll then become 4 on 4 (exception being coincidental fighting majors). Otherwise it'll stay the same situation. So if it's multiple penalties apiece, even if they're equal on both teams (say 3 roughing calls per team), then it'll stay 5 on 5. If one team is already shorthanded, then it'll remain 5v4 (or 5v3 or whatever).