Critical Hits in D&D 5e (Explained): Nat 20s, Damage, and Auto-Crit Rules
16 May 2026
A critical hit is the table’s applause cue. The fighter rolls a natural 20, everyone leans in, and suddenly you are rolling twice as many damage dice. It is simple until someone tries to double the +5 too.
For the full fight structure, see how D&D combat works. For when advantage stacks into crit fishing, see advantage and disadvantage.
The core rule
When you score a critical hit:
- You still need a valid attack roll that hits (natural 20 hits regardless of AC).
- Roll all of the attack’s damage dice twice and add the same modifiers once.
Example: longsword 1d8 + 4 Strength. Crit damage is 2d8 + 4, not 2d8 + 8.
Spell attacks and crits
Spell attacks can crit on a natural 20. Roll the spell’s damage dice twice. Do not double ongoing effects like hex bonus dice unless a feature says so; those are separate riders.
Cantrips scale with character level, so a late-game fire bolt crit hurts. That is working as designed.
Automatic critical hits
Some rules skip the nat 20 requirement:
- Paralyzed or unconscious creatures: melee hits from within 5 feet that hit are critical hits. See paralyzed and unconscious.
These are not “free crits on a miss.” You still need an attack roll that hits, but any hit becomes a crit.
Common mistakes
| Mistake | Fix |
|---|---|
| Doubling Strength or proficiency | Double dice only |
| Doubling sneak attack dice separately twice | Sneak attack is part of the attack; roll those dice twice with the rest |
| Critting on saving throws | Nat 20 on saves does not auto-crit damage |
| Declaring crit before confirming hit | Natural 20 always hits; other crit riders still need a hit |
Table speed tip
Say it out loud: “Crit, so double dice.” Roll weapon dice together, then add modifiers once. Saves the night from math debates.
Design note for DMs
Crits swing hard on low-level tables. If fights feel swingy, use fewer monsters with more HP instead of banning crits. Players love them; they are part of the game’s emotional rhythm.
Recommended gear
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Search Dungeons & Dragons on Amazon — opens a category search; pick what your table actually uses.