Constitution (CON) measures health, stamina, and vital force. It determines how many hit points you have, how well you resist physical threats via Fortitude saves, and — critically — the negative HP threshold at which you die. Every class benefits from a high CON; no class can afford to ignore it entirely.

What Constitution Affects

Stat / Check How CON applies
Hit points CON modifier × character level added to total HP; retroactive when CON changes
Fortitude saving throw CON modifier added to all Fortitude saves
Death threshold You die when your negative HP total equals or exceeds your CON score (e.g. CON 14 → dead at −14 HP)
Concentration checks CON modifier added to concentration checks (arcane casters only — divine casters use WIS)
Favored class HP bonus If you take the +1 HP favored class bonus each level, this stacks on top of the CON modifier × level total

Hit Points per Level

At 1st level you take the maximum value of your Hit Die. At each subsequent level you roll your Hit Die and add your CON modifier; the result is never less than 1.

Hit Die Classes Average / level
d6 Alchemist, Bard, Sorcerer, Wizard 3 + CON
d8 Cleric, Druid, Monk, Rogue, Summoner 4 + CON
d10 Fighter, Magus, Paladin, Ranger 5 + CON
d12 Barbarian 6 + CON
CON changes are retroactive. If your CON score permanently increases or decreases (ability drain, level-up stat bump, magic item), your HP total adjusts immediately — +1 HP per level per point of CON modifier gained or lost. Temporary CON bonuses (spells, rage) grant temporary HP instead.

The Death Threshold

You die when your negative HP total equals or exceeds your CON score (not modifier). The three states between 0 HP and death:

HP range Condition Key effect
0 HP Disabled One action per round (standard or move, not both); strenuous actions deal 1 damage
−1 to −(CON−1) Dying Unconscious; lose 1 HP per round unless stabilized; Fort DC 10 + |HP| to stabilize
−CON or worse Dead No further saves; requires raise dead or similar magic to return
No CON score. Constructs and undead do not have a CON score (listed as "—"). They do not make Fortitude saves against effects that require a living target, have no death threshold (they are destroyed at 0 HP), and do not benefit from effects that restore HP based on CON (such as aid).