Warhammer Damage Calculator

Your essential tool for theory-crafting and optimizing army lists in Warhammer 40,000 10th Edition.

Expected Outcome

0.00

Average Final Damage Dealt

• Expected Hits: 0.00
• Expected Wounds: 0.00
• Expected Failed Saves: 0.00

Chart: The Damage Funnel

What is a Warhammer Damage Calculator?

A warhammer damage calculator is a statistical tool used by Warhammer 40,000 players to predict the average outcome of an attack sequence. Instead of relying on gut feeling, this calculator processes the core statistics of an attacker and a defender—like Ballistic Skill, Strength, Armour Penetration, and Toughness—to output the probable number of wounds a target will suffer. It’s an indispensable resource for “Mathhammer,” the practice of using probability to make informed strategic decisions.

This tool is for any player, from a newcomer trying to understand the core mechanics to a seasoned tournament veteran looking to optimize their army list. By understanding the probable damage output, you can better decide which units to engage, which targets to prioritize, and whether a risky charge is worth the potential reward. Common misunderstandings often arise from the layered probabilities; a high number of attacks may seem powerful, but this calculator demonstrates how quickly they can be nullified by poor hit rolls, tough targets, or good armor saves.

Warhammer Damage Calculator Formula and Explanation

The core of Warhammer damage calculation is a sequence of probabilities, often called the “damage funnel.” Each step filters the initial number of attacks, reducing the total until only the final damage remains. The formula is a multiplication of these probabilities.

Expected Damage = (Attacks) × P(Hit) × P(Wound) × P(Fail Save) × (Damage) × P(Fail FNP)

Where:

• P(Hit): The probability of a successful hit roll, based on BS/WS.
• P(Wound): The probability of a successful wound roll, determined by comparing weapon Strength to target Toughness.
• P(Fail Save): The probability of the defender failing their best available save (armour or invulnerable), modified by the weapon’s AP.
• P(Fail FNP): The probability of the defender failing their “Feel No Pain” roll to ignore the damage.

Variables Table

Key variables in a damage calculation.

Variable	Meaning	Unit / Type	Typical Range
Attacks	Number of dice rolled to hit	Integer	1 – 30+
Skill (BS/WS)	Target number for a hit roll	X+ (on a d6)	2+ to 6+
Strength (S)	Power of the weapon	Integer	3 – 16+
Toughness (T)	Resilience of the target	Integer	3 – 14+
Armour Penetration (AP)	Reduces the target’s armour save	Modifier	0 to -6
Save (Sv)	Target number for an armour save	X+ (on a d6)	2+ to 6+
Damage (D)	Wounds inflicted per failed save	Integer	1 – 12

Practical Examples

Example 1: Intercessors vs. Ork Boyz

A squad of 5 Intercessors (10 attacks with Bolt Rifles) shoots at a unit of Ork Boyz.

• Inputs: 10 Attacks, 3+ BS, S 4, T 5, AP -1, 5+ Save, D 1.
• Calculation:
  • Hits: 10 * (4/6) = 6.67
  • Wounds (S4 vs T5 is 5+): 6.67 * (2/6) = 2.22
  • Failed Saves (5+ save becomes 6+ due to AP-1): 2.22 * (5/6) = 1.85
  • Result: Approx. 1.85 damage, likely killing one or two Ork Boyz.

Example 2: Lascannon vs. Leman Russ Tank

A single Lascannon shot targets a Leman Russ Battle Tank.

• Inputs: 1 Attack, 3+ BS, S 12, T 11, AP -3, 2+ Save, D 6 (average of d6+2).
• Calculation:
  • Hits: 1 * (4/6) = 0.67
  • Wounds (S12 vs T11 is 3+): 0.67 * (4/6) = 0.44
  • Failed Saves (2+ save becomes 5+ due to AP-3): 0.44 * (4/6) = 0.29
  • Final Damage: 0.29 * 6 = 1.74 damage.

How to Use This Warhammer Damage Calculator

Using this warhammer damage calculator is straightforward. Follow these steps to get an accurate analysis of your unit’s potential.

1. Enter Attacker Stats: Begin by inputting the total number of attacks, the required roll to hit (BS or WS), and the weapon’s Strength.
2. Enter Defender Stats: Input the target’s Toughness, its base Armour Save, and its Invulnerable Save (if any). Use ‘7’ for saves that don’t exist.
3. Set Weapon Profile: Enter the Armour Penetration (as a positive number, e.g., 1 for AP-1) and the weapon’s Damage characteristic.
4. Add Special Rules: If the target has a Feel No Pain ability, enter the required roll (e.g., 5 for 5+).
5. Calculate and Interpret: Click the “Calculate” button. The primary result shows the average total damage you can expect. The intermediate values show you where your attacks are succeeding or failing in the damage sequence.

Key Factors That Affect Damage Output

Several critical factors can drastically alter the outcome of an attack. A good player understands how these interact.

• Strength vs. Toughness Breakpoints: The relationship between Strength and Toughness is paramount. Wounding on a 2+ versus a 6+ is the difference between an effective weapon and a useless one.
• Armour Penetration (AP): High AP is crucial for defeating heavily armored targets. An AP of -2 or better can force even elite infantry to rely on their inferior invulnerable saves.
• Volume of Fire vs. Quality of Shots: Sometimes, many weak shots (like from a Guardsman’s lasgun) can overwhelm a target through sheer numbers, while other situations demand a single, high-quality shot (like a Melta weapon). Our Mathhammer guide can help you decide.
• Invulnerable Saves: An invulnerable save is a powerful defensive tool because it cannot be modified by AP. A 4++ invulnerable save is a consistent defense against any weapon.
• Feel No Pain (FNP): This acts as a final layer of defense, providing a chance to ignore damage after a save has already been failed. It is particularly effective against high-damage weapons.
• Re-rolls: Though not modeled in this basic calculator, the ability to re-roll hits or wounds is one of the most powerful buffs in the game, significantly increasing expected damage.

Frequently Asked Questions (FAQ)

1. How do I handle variable damage (e.g., D6)?

For variable damage like D6, use the average value. For a D6, the average is 3.5. For a D3, the average is 2. This calculator uses a single value for simplicity, so inputting the average gives a good estimate.

2. Does this calculator account for re-rolls?

No, this is a basic warhammer damage calculator and does not include the complex logic for re-rolling dice. Re-rolls significantly increase probability and would require a more advanced tool like our upcoming Advanced Stats Engine.

3. What’s the difference between an Armour Save and an Invulnerable Save?

An Armour Save is modified by the AP of an attack, while an Invulnerable Save is not. You always use the better of the two available saves. For example, a model with a 3+ save and a 5++ invulnerable save, when hit by an AP -3 weapon, would have its armour save modified to a 6+ but could still use its 5++ invulnerable save.

4. Why is the result a decimal? I can’t deal 1.85 damage.

The result is a statistical average, not a guaranteed outcome for a single roll. Over many rounds of combat, the damage you deal will trend towards this average. It represents the probability-weighted outcome of thousands of potential dice rolls.

5. Does damage “spill over” to other models?

No. Each attack is resolved separately. If one attack deals 10 damage to a model with only 2 wounds left, the extra 8 damage is lost and does not “spill over” to another model in the unit. The only exception is Mortal Wounds.

6. How are the Strength vs. Toughness wound rolls determined?

The roll needed to wound is: 4+ if S=T, 3+ if S > T, 2+ if S is at least double T, 5+ if S < T, and 6+ if S is half of T or less.

7. Can I use this for Warhammer: Age of Sigmar?

While the core concepts are similar, Age of Sigmar has different mechanics (e.g., “Rend” instead of “AP,” different wound charts). This calculator is specifically designed for Warhammer 40,000 10th Edition. You can find an AoS calculator here.

8. What does a “7” for a save mean?

Entering ‘7’ signifies that the model does not have that type of save, as it’s impossible to roll a 7 on a standard six-sided die. This effectively makes the probability of success zero.