40k Damage Calculator

Use this 40k damage calculator to project expected hits, wounds, failed saves, and total damage for Warhammer 40k attacks, all in one clean and responsive layout.

40k Damage Calculator Inputs

Formula: Expected Damage = (Attacks × Hit Probability × Wound Probability × Save Fail Probability × Damage per Successful Attack) + Mortal Wounds.

Chart shows comparative expected wounds before saves and final expected damage.

Stage	Value	Explanation
Attacks	–	Number of dice rolled.
Expected Hits	–	Attacks × Hit Probability.
Expected Wounds	–	Expected Hits × Wound Probability.
Failed Saves	–	Expected Wounds × Save Fail Probability.
Total Damage	–	Failed Saves × Damage per Successful Attack + Mortal Wounds.

Intermediate breakdown helps optimize profiles and buffs in the 40k damage calculator.

What is 40k damage calculator?

The 40k damage calculator is a focused tool that estimates how many wounds and how much damage an attack sequence will inflict in Warhammer 40,000. Players who want to plan target priorities, evaluate weapon profiles, or compare buffs rely on the 40k damage calculator to visualize outcomes before committing to a strategy. A common misconception is that the 40k damage calculator is only for mathhammer experts, but it actually simplifies the probabilities so any commander can make fast decisions.

40k damage calculator Formula and Mathematical Explanation

The 40k damage calculator multiplies each stage of the attack chain: attacks, hit probability, wound probability, save fail probability, and damage per successful attack. Mortal wounds are then added because they bypass saves. By chaining these probabilities, the 40k damage calculator provides the expected value of damage across many rolls.

Step-by-step derivation:

1. Expected Hits = Attacks × Hit Probability
2. Expected Wounds = Expected Hits × Wound Probability
3. Failed Saves = Expected Wounds × Save Fail Probability
4. Base Damage = Failed Saves × Damage per Successful Attack
5. Total Expected Damage = Base Damage + Mortal Wounds

Variable	Meaning	Unit	Typical Range
Attacks	Number of dice rolled	count	1 – 60
Hit Probability	Chance each attack hits	0-1	0.5 – 0.833
Wound Probability	Chance a hit wounds	0-1	0.333 – 0.833
Save Fail Probability	Chance defender fails save	0-1	0.167 – 0.833
Damage per Successful Attack	Average damage per unsaved wound	damage	1 – 6
Mortal Wounds	Flat wounds bypassing saves	wounds	0 – 6

Variables table clarifies inputs required by the 40k damage calculator.

Practical Examples (Real-World Use Cases)

Example 1: Intercessor Volley

Inputs: Attacks 20, Hit Probability 0.6667 (3+), Wound Probability 0.5 (S4 vs T4), Save Fail Probability 0.333 (AP0 vs 3+), Damage per Successful Attack 1, Mortal Wounds 0. The 40k damage calculator outputs Expected Damage ≈ 2.22, with about 13.33 hits and 6.67 wounds before saves.

Example 2: Melta Strike with Buffs

Inputs: Attacks 4, Hit Probability 0.833 (2+ with reroll 1s), Wound Probability 0.6667 (S8 vs T7), Save Fail Probability 0.6667 (AP-4 vs 4++), Damage per Successful Attack 4, Mortal Wounds 1. The 40k damage calculator shows Expected Damage ≈ 9.78, making it ideal against heavy targets.

How to Use This 40k damage calculator

1. Enter the number of attacks your unit makes.
2. Set hit probability based on hit roll and rerolls.
3. Set wound probability based on strength versus toughness.
4. Enter save fail probability after AP, cover, and invulnerable effects.
5. Add damage per successful attack and any mortal wounds.
6. Read the highlighted expected damage and review intermediate values for precision.

Use the 40k damage calculator results to choose optimal targets, decide on CP rerolls, and evaluate whether to split fire or focus fire.

Key Factors That Affect 40k damage calculator Results

• Hit roll modifiers and rerolls directly change the hit probability in the 40k damage calculator.
• Strength versus toughness shifts wound probability and can swing outcomes dramatically.
• AP values alter save fail probability; small AP changes compound through the 40k damage calculator chain.
• Damage characteristics, including minimum damage on melta or d3 weapons, influence average damage per attack.
• Mortal wounds bypass saves and add linear value in the 40k damage calculator outputs.
• Target defensive buffs like transhuman or invulnerable saves reduce effective wound or save probabilities.
• Number of attacks from rapid fire, extra hits on 6s, or stratagems increases the baseline for the 40k damage calculator.
• Cover and armor of contempt style rules reduce save fail probability, lowering total output.

Frequently Asked Questions (FAQ)

Does the 40k damage calculator handle rerolls?

Yes, convert rerolls into an adjusted probability before entering values in the 40k damage calculator.

Can I include mortal wounds on critical hits?

Add the average mortal wounds to the mortal wound field in the 40k damage calculator.

How do swingy d3 or d6 damage weapons work?

Use the average damage value (2 for d3, 3.5 for d6) in the 40k damage calculator.

What about Feel No Pain style saves?

Multiply damage by the failure rate of the FNP and adjust damage per attack in the 40k damage calculator.

Can this handle exploding 6s?

Increase the number of attacks or hit probability to account for extra hits when using the 40k damage calculator.

How accurate is the expected damage?

The 40k damage calculator provides averages; actual dice will vary but follow the same expectation.

Does cover change wound probability?

Cover usually affects saves, so adjust save fail probability in the 40k damage calculator accordingly.

Can I copy results for list planning?

Yes, use the copy button to export current 40k damage calculator results and assumptions.

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