Rolling Health

[JobsforFun]

I was wondering lets say you have a +2 to constitution and you roll your health and all is fine, but when you get to the next level you get a ability score improvement and raise your constitution modifier to a +3 do you roll your health for that next level and add +3 or do you re-roll you health entirely as if you had always had the new modifier?

[Malifice]

I was wondering lets say you have a +2 to constitution and you roll your health and all is fine, but when you get to the next level you get a ability score improvement and raise your constitution modifier to a +3 do you roll your health for that next level and add +3 or do you re-roll you health entirely as if you had always had the new modifier?

Bonuses are retroactive.

You dont reroll, you just recalculate based on whatever you rolled (plus the new mods).

[JobsforFun]

Bonuses are retroactive.

You dont reroll, you just recalculate based on whatever you rolled (plus the new mods).

I'm slightly confused, is there a page in the PHB discussing this?

[Maxilian]

Bonuses are retroactive.

You dont reroll, you just recalculate based on whatever you rolled (plus the new mods).

That means that if:

You're a Fighter 5 with 15 HP (Random Number) with +2 CON, and when you lvl up, you use the new ASI to get your CON to +3, you will first calculate the new HP of that lvl 1d10 +3, and then check how much the ASI increased (in this case 1) and multiply that with the quantity of lvls you had before lvling up (5) (so 1 x 5 = 5) and you add that amount to the total of your HP (so you will have 15 HP + (1D10 +3) + 5)

Note: it sounds more complicated than what it is (i just wanted to go in detail)

[Malifice]

I'm slightly confused, is there a page in the PHB discussing this?

The easy way to put it is if your Con goes up from +2 to +3 at (say) 8th level, add 7 HP to your previous total (to account for the increase in your Con bonus for levels 1-7) before rolling your new [HD+3].

Is about the clearest I can make it.

[Millstone85]

I'm slightly confused, is there a page in the PHB discussing this?It is on page 15.
When your Constitution modifier increases by 1, your hit point maximum increases by 1 for each level you have attained.

[D.U.P.A.]

Otherwise there would be no point to increase constitution.