How to Use the Multi-Attack Calculator
- Enter the number of attacks granted by Extra Attack, Multiattack, off-hand strikes, or bonus-action attacks.
- Add your total attack bonus (ability modifier + proficiency + magic weapon bonuses) and the target’s Armor Class.
- Define each attack’s damage dice, optional recurring bonus dice, and static damage modifiers.
- Select the critical range (20 for most builds, 19-20 for expanded crit features) and whether the roll has advantage or disadvantage.
- Press Calculate Multi-Attack or hit the space bar to instantly see hit chance, crit chance, expected damage per attack, total DPR, and theoretical maximums.
Multiattack vs Extra Attack (5e)
Extra Attack is a class feature that adds more attacks when you take the Attack action. Multiattack is typically a monster or NPC action that specifies exactly which attacks are made (for example, two claws and one bite).
This calculator models the math of multiple attack rolls in a round (hit chance, crit chance, and expected damage). For mixed multiattacks with different damage dice, set each attack row to match the exact profile.
Multi-Attack Formula (D&D 5e)
Hit when: d20 + Attack Bonus ≥ Target AC (natural 1 misses; natural 20 hits and is typically a critical hit).
Expected DPR is driven by three things: hit chance, crit chance, and your average damage on a hit (including bonus dice and static modifiers).
- Advantage: roll 2d20 and keep the higher die (higher hit + crit chances).
- Disadvantage: roll 2d20 and keep the lower die (lower hit + crit chances).
- Critical hits: usually double damage dice, but add static modifiers once.
Example: If you make 2 attacks with +7 to hit vs AC 16, your minimum d20 roll to hit is 9 (because 9 + 7 = 16). Advantage increases the chance that at least one die meets or beats 9.
Features for Martial Classes
- Accurate Hit Math: Uses true d20 probabilities with automatic natural 1 failures and natural 20 successes.
- Advantage/Disadvantage Support: Calculates the adjusted probabilities for crits and hits when rolling twice.
- Flexible Dice Inputs: Model versatile weapons, great weapon master, recurring riders like Hunter’s Mark or Hex, or elemental weapon dice. For Great Weapon Master, subtract 5 from attack bonus and add 10 to the damage modifier for those attacks.
- History Tracking: Compare up to eight previous calculations when testing fighting styles, feats, or new weapons.
- Max Damage Insights: Shows theoretical maximums (all attacks crit) so you can compare burst potential across setups.
D&D 5e Rules Behind the Numbers
In D&D 5e, every attack roll is a d20 modified by your attack bonus. A natural 1 always misses, while a natural 20 always hits and becomes a critical hit. Most classes gain Extra Attack at level 5, giving two attacks per Attack action. Some monsters have Multiattack that grants two or more strikes with a single action. Bonus actions (such as off-hand dual-wield attacks or Polearm Master butt strikes) add even more attack instances per round.
Critical hits double the damage dice but not your static modifiers. Improved Critical (Champion fighter) expands the crit range to 19-20, while certain magic items or house rules might go to 18-20. Advantage means you roll twice and keep the higher result, which increases both hit chance and crit chance; disadvantage does the opposite.
Tips, Examples, and Strategy
A level 11 Fighter with Extra Attack (3) swinging a greatsword with Strength +5 and a +2 weapon attacks four times each round (three from the attack action, one from Polearm Master or bonus attack). Plug in 4 attacks, +11 attack bonus, target AC 18, weapon dice 2d6, and a +7 damage modifier. If you add a d6 from Hexblade’s Curse or Hunter’s Mark, include that under recurring bonus dice. Need advantage? Toggle it when a spell like Faerie Fire or the Help action is active. Use this calculator alongside the attack roller to resolve each strike, then confirm burst damage with the critical hit calculator if you land a nat 20. Dungeon Masters can evaluate monster multiattacks versus player AC to ensure encounter balance without complicated spreadsheets.
Example: 2 attacks, +7 to hit vs AC 16, 1d8+4
- Number of attacks: 2
- Attack bonus: +7
- Target AC: 16
- Weapon dice: 1d8
- Damage modifier: +4
Run this setup to compare Normal vs Advantage and see how crit chance and expected DPR change.
Example: Mixed multiattack (bite + claw + claw)
- Number of attacks: 3
- Attack bonus: +5
- Target AC: 15
- Attack 1: 1d8 + 3 (bite)
- Attack 2: 1d6 + 3 (claw)
- Attack 3: 1d6 + 3 (claw)
Set each row to the matching damage profile so the DPR total reflects the mixed attack sequence.
Multi-Attack DPR FAQ
What is DPR in D&D?
DPR means damage per round. It’s the expected average damage you deal in one round, factoring in hit chance, crit chance, and how many attacks you make.
How do you calculate hit chance versus AC in D&D 5e?
An attack hits when d20 + attack bonus ≥ target AC. A natural 1 misses, and a natural 20 hits (and is typically a crit) on attack rolls.
How do critical hits affect expected damage?
On a critical hit, you typically roll the attack’s damage dice twice and add flat modifiers once. This increases expected damage, especially for builds with lots of bonus damage dice.
How does advantage or disadvantage change DPR?
With advantage you roll 2d20 and keep the higher die; with disadvantage you keep the lower die. Advantage increases both hit chance and crit chance, while disadvantage decreases them.
Does this calculator include bonus damage dice like Hunter’s Mark?
Yes. Add any recurring bonus damage dice (like a d6 rider) and the calculator includes them in average damage and crit doubling.
What’s the difference between Multiattack and Extra Attack?
Extra Attack is a class feature that adds more attacks when you take the Attack action. Multiattack is a monster or NPC action that specifies exactly which attacks are made.
Can player characters use Multiattack?
Typically no. Player characters use Extra Attack or features that grant additional attacks, while Multiattack is usually reserved for monster or NPC stat blocks.
Is this tool only for D&D 5e?
It’s tuned to the 5e-style d20 + bonus vs AC system with nat 1/nat 20 rules for attack rolls. For other systems, treat results as an approximation.