D&D Critical Hit Damage Calculator

Enter the weapon dice, flat modifier, sneak attack, smite, or other bonus dice and roll the crit damage immediately. The tool shows normal hit vs critical hit so you can see exactly which dice double.

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Damage Dice

What doubles on a crit?

Weapon dice, Sneak Attack dice, Divine Smite dice, and other damage dice are rolled twice. Static modifiers such as Strength, Dexterity, magic weapon bonuses, and other flat bonuses are added once.

Damage Comparison

Normal Hit

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Critical Hit

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Average Damage

Normal average damage -
Critical average damage -
Average crit bonus -
Normal damage range -
Critical damage range -

Recent Rolls

Compare the last six damage rolls to track normal hit and critical hit results.

No rolls yet.

Need the attack roll first?

Use the D&D attack roller to confirm the hit, then compare crit damage here. For several attacks in one turn, use the multi-attack calculator, or roll custom dice with the D&D dice roller.

How to Use the Critical Hit Calculator

  1. Enter your weapon damage dice, such as 1d8 for a longsword or 2d6 for a greatsword.
  2. Add your static damage modifier (usually Strength or Dexterity plus magic weapon bonus).
  3. Specify extra dice like sneak attack (d6) or divine smite (d8) by entering the number of dice rolled.
  4. Press Roll Damage. The calculator rolls once for a normal hit and again with doubled dice for a critical hit, keeping modifiers applied once.
  5. Review the breakdowns to see exactly which dice contributed to the total. Recent rolls stay in the history for quick reference.

Critical Hit Damage Formula (D&D 5e)

Critical Hit Damage = (All damage dice rolled twice) + (static modifiers added once)

On a critical hit, you typically double the number of damage dice you roll (weapon dice and any bonus damage dice from features), but you do not double flat bonuses like Strength/Dexterity modifiers.

  • Weapon dice: doubled (e.g. 1d8 becomes 2d8 on a crit)
  • Bonus damage dice: doubled (e.g. Sneak Attack dice, Divine Smite dice)
  • Static bonuses: added once (ability modifier, magic weapon bonus)

Example: 1d8 + 4 weapon hit becomes 2d8 + 4 on a crit. If you add 3d6 Sneak Attack, it becomes 2d8 + 6d6 + 4.

What This Crit Calculator Handles

  • Weapon Dice Control: Input any combination of dice to model versatile weapons and multi-die weapons (like 2d6 greatswords).
  • Bonus Dice Options: Sneak attack, divine smite, and a custom extra dice slot cover most class features.
  • Normal vs Critical: View both results side-by-side to evaluate the impact of features like Improved Critical.
  • History Log: Track up to six damage rolls across normal and critical hit results.
  • Transparent Dice: The breakdown shows every individual die, so your DM can see the actual results.

Critical Hit Rulings to Check at the Table

In 5th Edition, a natural 20 on an attack roll is a critical hit. The usual ruling is to roll all damage dice for the attack twice, including weapon dice, smite dice, sneak attack dice, and other extra damage dice from features or spells. Static modifiers such as ability bonuses, magic weapon bonuses, or Hexblade's Curse are added once.

Some tables use "max damage plus a normal roll" or other house rules for crits. This calculator uses the common RAW approach: doubled dice, modifiers once. If your DM uses a different crit rule, the normal and critical breakdowns still make it easy to compare the dice involved.

Examples and Tips

A level 9 rogue rolling a rapier attack would enter 1d8 weapon dice, +4 modifier, and 5d6 sneak attack dice. When a crit lands, the tool doubles both the weapon and sneak dice, instantly showing the burst potential. Paladins can enter their smite dice based on slot level; a 3rd-level smite adds 4d8 that double on a crit.

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