Saul, Nothing on the D&D 5e by Roll20 NPC sheet is calculated, not one single thing. Everything is manually entered onto the sheet. It is all a reproduction of the book. Yes, the DM CAN change it from the average. But that is not what is in the book unless the DM takes the option to roll the HP, in which case they have to do it manually, just like if they were playing with physical dice and paper. hp_max is not the maximum hp from a formula, it is the normal, undamaged hitpoints of the creature, whatever their normal undamaged value is. Current vs Maximum value . It is a programming thing, not a game mechanics thing. Regarding the rules in the book, nothing in them state anything like what you are saying. Here is a quote from the Monster Manual section on HP: "A monster's hit points are presented both as a die expression and as an average number. For example, a monster with 2d8 hit points has 9 hit points on average (2 x 4 1/2) A monster's size determines the die used to calculate its hit points, as shown in the Hit Dice by Size table. A monster's Constitution modifier also affects the number of hit points it has. Its Constitution modifier is multiplied by the number of Hit Dice it possesses, and the result is added to its hit points. For example, if a monster has a Constitution of 12 (+1 modifier) and 2d8 Hit Dice, it has 2d8 + 2 hit points (average 11)." (Note: I did not reproduce the table) The DM either takes the average (presented) or rolls the HP. It does not state a monster gets the maximum possible HP if the DM wants, ergo taking the maximum roll is a house rule. Ive been on Roll20 since nearly the beginning. Roll20's terminology often means something different from a game's terminology because there are 100s of games that are on Roll20 and Roll20's terminology is often based on programing meanings. In this case hp_max is a Roll20 meaning to contrast it from a creatures current HP. In any case, I don't feel like this is going anywhere. This can be summed up as a misunderstanding in the programming term of "hp_max" vs your understanding of "maximum" and a misunderstanding on how the NPC sheet works. Once again, the NPC sheet has no calculations in it. HP is not calculated at all. It is a simple reproduction of the creature in the book.