40K Visual Dice Calculator

1. Enter the attacker: fixed attacks and any attack dice, BS or WS, Strength, AP and Damage, plus weapon abilities such as Lethal Hits or Sustained Hits.
2. Enter the target: Toughness, Save, any invulnerable save or Feel No Pain, Wounds per model and the number of models.
3. Read the funnel. The bars show how attacks shrink into hits, wounds, failed saves and damage, and the result shows the models destroyed on average.

A 40K dice calculator is a probability tool for the Warhammer 40,000 attack sequence. It answers one question before you commit a unit: how much damage will this weapon do to that target, on average and at the extremes?

Players call this "mathhammer". It helps with target priority, list building and comparing two weapon profiles. It does not roll dice for you. The old version of this page rolled one random sample per click, which told you nothing about the odds. This version averages every possible roll exactly. For crit-based damage in other games, see how to calculate crit chance and damage.

The 11th edition Core Rules resolve each attack in four steps: hit roll, wound roll, save roll and inflict damage (section 05). The chance of damage is the product of the chances at each step.

1. Hit roll (05.01): an unmodified 1 always fails and an unmodified 6 is a critical hit. Any other roll hits when it equals or beats BS or WS after modifiers.
2. Wound roll (05.02): compare Strength with Toughness. S at least twice T wounds on 2+, S greater than T on 3+, S equal to T on 4+, S less than T on 5+, and S half of T or less on 6+. An unmodified 1 fails and an unmodified 6 is a critical wound.
3. Save roll (05.03 and 05.04): an unmodified 1 always inflicts damage. The roll saves if it meets the invulnerable save, or if it meets the armour save after AP is applied. AP -1 turns a roll of 3 into a 2.
4. Inflict damage: the model loses wounds equal to D. Extra damage past 0 wounds is lost, so D3 damage into 1-wound models wastes the surplus.

The tool then combines every attack exactly. Random attacks and random damage are spread over all their outcomes, never averaged first.

Ten attacks with BS 3+, S4, AP -1 and D1 target five models with T4, a 3+ save and 2 wounds each.

1. Hits: 3+ succeeds on 4 of 6 faces, so 10 x 4/6 = 6.67 hits.
2. Wounds: S4 equals T4, so 4+ is needed, which is 3/6. That gives 6.67 x 1/2 = 3.33 wounds.
3. Saves: AP -1 makes the 3+ save work like a 4+, so it fails half the time. That leaves 1.67 failed saves.
4. Models: each 2-wound model needs two failed saves. The exact result is 0.59 models destroyed on average, with a 51.5% chance to destroy at least one.

Averages hide the spread. The kill-chance bars show that destroying two or more models is much less likely than destroying none.

Strength Versus Toughness Breakpoints

The wound roll jumps at S = T, S greater than T and S = 2T. S5 into T4 wounds on 3+ (67%), but S4 into T4 needs 4+ (50%). One point of Strength can matter more than an extra attack.

AP Against the Save

Each point of AP worsens the armour save by one. An invulnerable save ignores AP, so high AP gains less against a 4+ invulnerable save.

Critical Hit Abilities

Lethal Hits and Sustained Hits trigger only on an unmodified 6, so each adds about one sixth of an extra effect per attack. Torrent attacks hit automatically and cannot score critical hits.

Damage and Wounds per Model

Damage is lost on overkill. D2 into 1-wound models is no better than D1. D3 into 3-wound models destroys a model only on a 3.

Re-rolls and Modifiers

Re-rolls happen before modifiers, and a die can be re-rolled once. Modifiers to hit and wound rolls stop at -1 or +1, no matter how many apply.

Lethal Hits and Devastating Wounds interact. An automatic wound from Lethal Hits is not a critical wound, so it cannot trigger Devastating Wounds. This tool assumes you take the automatic wound. The rules let you decline it.

Choosing a Target in the Shooting Phase

Compare the same weapon into two enemy units and shoot where the kill chance is highest.

Building an Army List

Test two weapon options into the targets you expect to face. A small gain in average damage may not be worth the points.

Checking a Close Game

Before a key charge, see the chance to finish a unit. A 40% wipe chance calls for a backup plan.

1. Getting AP Backwards

AP makes saves worse. A 3+ save against AP -1 acts as a 4+, not a 2+. The old tool on this page made this error.

2. Stacking Modifiers Past One

Two -1 hit penalties still give only -1. Adding them wrongly makes a weapon look weaker than it is.

3. Counting Overkill as Damage

Six D3 damage into 1-wound models can destroy at most six models, whatever the damage rolls.

4. Using Both Saves

A model makes one save roll. The invulnerable save and armour save are two ways to pass that one roll, not two chances.

5. Forgetting That a 1 Always Fails

Even at BS 2+ with +1 to hit, a 1 misses. Your best hit chance is 5/6 without re-rolls.

6. Trusting One Roll

A single roll can swing wildly. Use averages and chances, then plan for bad luck. The same idea drives dice probability in general.

The odds are exact for the rules modelled here, because the tool sums every outcome instead of simulating.

You need a 4+, a 50% chance, because Strength equals Toughness. At S5 you need 3+, and at S8 you need 2+.

No. AP modifies only the armour save roll. An invulnerable save is checked on the unmodified result.

A 3+ hits 4 times in 6, or 66.7%. Re-rolling 1s raises it to 77.8%, and re-rolling all misses raises it to 88.9%.

It adds one extra hit for each unmodified 6, so about one sixth of a hit per attack. Ten attacks gain 1.67 hits on average, whatever the BS.

No. A Lethal Hits auto-wound skips the wound roll, so it cannot be a critical wound. You can decline the auto-wound to roll instead.

Roll one D6 and halve it, rounding up. A 1 or 2 gives 1, a 3 or 4 gives 2, and a 5 or 6 gives 3.

Damage past a model's last wound is lost. D6 damage into 2-wound models wastes most of each roll.

Yes. Feel No Pain is rolled for each wound a model would lose, from normal damage or mortal wounds.

It follows the 11th edition Core Rules released on 1 June 2026, with the Universal Rules Updates version 1.1 that applies from 26 August 2026.

Yes. Enter WS in the BS or WS field. Melee and ranged attacks use the same hit, wound and save steps.

No. It is a free fan-made tool. Warhammer 40,000 and 40K are trademarks of Games Workshop Limited. This fan-made calculator is not affiliated with or endorsed by Games Workshop.

• #New40k Rules: download the free Core Rules now (Warhammer Community, Games Workshop, 1 June 2026). Official announcement of the 11th edition Core Rules.
• Warhammer 40,000 downloads: Core Rules and Universal Rules Updates (Warhammer Community). Official free Core Rules PDF, sections 05 and 24 used here, and the Universal Rules Updates 1.1.
• Rules appendix, 11th edition (Wahapedia, community rules reference). Modifier cap of -1 or +1 and the re-roll-once rule.
• OpenStax section 3.2 Independent and Mutually Exclusive Events (OpenStax). Why independent step chances multiply.