Missing Hitpoint Total

Your missing hitpoint total is equal to the difference between your current hitpoint total and your maximum hitpoint total. For example, Archibald the cleric enters a combat encounter at full health with 81 hitpoints. He takes 26 points of hitpoint damage and 8 points of nonlethal damage during the encounter, which leaves him at 47 hitpoints. He then casts false life and gains 12 temporary hitpoints, which brings him back up to 59 hitpoints. At this point in time, Archibald's missing hitpoint total is equal to 81 - 59 = 22.