Damage and Hit Points Rules

Damage and hit points form the foundational resource-tracking system that governs survival, attrition, and combat resolution in Dungeons & Dragons. These rules determine how creatures absorb harm, when they fall unconscious, and how recovery functions between encounters. The mechanics connect directly to the broader combat rules framework and interact with conditions, death states, and healing across every tier of play.

Definition and scope

Hit points (HP) represent a combination of physical endurance, fighting instinct, and luck — not exclusively flesh wounds. The Player's Handbook (5th edition, Wizards of the Coast) describes HP as a measure of a creature's ability to avoid debilitating injury, meaning a hit point loss does not necessarily correspond to a gaping wound.

Every creature has a hit point maximum, a fixed upper limit determined by class, Constitution modifier, and level. At character creation — see character creation rules — a player typically takes the maximum die value at 1st level, then rolls or averages on subsequent levels. A Fighter with a d10 hit die and a +2 Constitution modifier begins with 12 HP at 1st level.

Temporary hit points (temp HP) occupy a separate pool that absorbs damage before the main pool is reduced. Temp HP from different sources do not stack; only the higher value applies. This distinction matters when adjudicating spells like False Life or class features like the Barbarian's Rage.

Damage types recognized by the core rules include 13 categories: acid, bludgeoning, cold, fire, force, lightning, necrotic, piercing, poison, psychic, radiant, slashing, and thunder. Resistance halves damage of a given type (rounded down); immunity negates it entirely; vulnerability doubles it.

How it works

When an attack hits — after the attack rolls and armor class check resolves — the attacker rolls the weapon's or spell's damage dice and adds the relevant modifier. That total is subtracted from the target's current HP.

Standard damage calculation sequence:

  1. Confirm the attack hits by comparing the attack roll to the target's AC.
  2. Roll the damage dice specified by the weapon, spell, or feature.
  3. Add the appropriate ability modifier (Strength for melee, Dexterity for finesse/ranged, spellcasting modifier for spells).
  4. Apply any damage modifiers from feats, class features, or magical effects.
  5. Apply resistance or vulnerability (never both simultaneously — resistance is applied first if a creature somehow qualifies for both).
  6. Subtract the final total from current HP.

Critical hits occur on a natural 20 attack roll. On a crit, the attacker rolls all damage dice twice (not the modifier) before adding the modifier. A Rogue's Sneak Attack dice, for example, are doubled on a crit — a significant burst-damage mechanic at higher levels.

The distinction between saving throws and attack rolls matters here: spell damage triggered by a failed saving throw does not generate critical hits, since there is no attack roll involved.

Common scenarios

Massive damage and instant death: If damage reduces a creature to 0 HP and the remaining damage equals or exceeds the creature's HP maximum, it dies outright. A character with a maximum of 10 HP, currently at 5 HP, struck for 20 damage triggers this rule.

Dropping to 0 HP: Player characters who reach 0 HP fall unconscious and begin making death saving throws — a separate sub-system detailed in death and dying rules. Monsters, by default, die at 0 HP rather than falling unconscious.

Healing: HP can be restored by spending Hit Dice during a short rest or regaining all lost HP on a long rest, per resting rules. Spells such as Cure Wounds add the caster's spellcasting modifier to the dice rolled. Healing cannot exceed a creature's HP maximum; excess healing is lost.

Area damage and saving throws: Many spells — Fireball, Thunderwave — deal damage to every creature in a defined area. Affected creatures make a Dexterity saving throw; success halves the damage. The Rogue's Evasion feature allows a successful save to negate damage entirely, and a failed save still halves if the Rogue has the feature — making it among the most valuable defensive class abilities in the system.

Concentration and damage: When a spellcaster sustains damage while concentrating on a spell, a Constitution saving throw is required (DC 10 or half the damage taken, whichever is higher). Failing drops the spell. This is covered fully under concentration rules.

Decision boundaries

Two critical distinctions govern edge cases:

Resistance vs. immunity: Resistance halves damage (round down). Immunity negates all damage. A creature resistant to fire taking 15 fire damage takes 7. A creature immune to fire takes 0. These are not interchangeable and should not be treated as degree differences on a spectrum.

Temp HP vs. real HP: Temp HP is not real HP and cannot be restored by healing. A Paladin casting Cure Wounds on a character who has only temp HP remaining does not increase total HP — it restores from the permanent pool if that pool is below maximum. Temp HP functions as a one-way buffer.

The optional and variant rules section of the Dungeon Master's Guide introduces alternatives such as Lingering Injuries and Massive Damage tables that change what happens at 0 HP or during severe strikes — tools that shift the system toward grittier, more simulationist play. These are not part of the default ruleset.

For a broader orientation to how recreational systems like D&D are structured as hobby frameworks, the how-recreation-works-conceptual-overview page and the full site index provide additional structural context.

References

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