Calculate Your 40k Combat Outcomes
Combat Outcome Visualisation
This chart visually represents the average progression of your attacks from hits to final damage.
What is a 40k Dice Calculator?
A 40k dice calculator is an indispensable online tool designed for players of Warhammer 40,000 to predict the statistical outcomes of dice rolls in combat scenarios. Instead of manually rolling dice hundreds of times or performing complex mental math, this calculator automates the process, providing average hits, wounds, saves, and ultimately, total damage dealt.
This tool is particularly useful for:
- Army List Building: Evaluate the offensive potential of different unit compositions and weapon loadouts.
- Strategic Planning: Understand the reliability of your units against various enemy profiles before a game.
- Rules Clarification: See the impact of modifiers, re-rolls, and special rules like Armour Penetration (AP) and Feel No Pain (FNP) in a tangible way.
- Learning Game Mechanics: New players can grasp the sequential nature of 40k combat more easily.
Common misunderstandings often revolve around the impact of re-rolls or how multiple modifiers stack. For instance, a re-roll of 1s is significantly different from a full re-roll of failed rolls, and knowing the statistical difference can be game-changing. This calculator helps clarify these nuances by showing the average numerical impact.
40k Dice Calculator Formula and Explanation
The calculations performed by a 40k dice calculator follow the sequential logic of Warhammer 40,000 combat. It's a chain of probabilities, where the success of one stage feeds into the next. The core principle is calculating the probability of a specific dice roll succeeding, then factoring in re-rolls and modifiers.
Core Probability Calculation (Success on a D6 for X+):
The chance of rolling an X+ on a D6 is `(7 - X) / 6`. For example, a 3+ roll has a `(7 - 3) / 6 = 4/6 = 0.666...` probability.
Modifiers adjust the effective target. A +1 modifier on a 3+ roll makes it a 2+ roll for calculation purposes. An AP value for saves also modifies the target save roll.
Re-roll Mechanics:
- Re-roll 1s: If a die rolls a 1 and fails, it gets a second chance. The probability is `P(Success) + P(Roll is 1 AND Fails) * P(Success on Re-roll)`.
- Re-roll Failed: If a die fails its initial roll, it gets a second chance. The probability is `P(Success) + P(Failure) * P(Success on Re-roll)`.
Sequential Combat Formula:
- Average Hits:
Number of Attacks * P(Hit) - Average Wounds:
Average Hits * P(Wound) - Average Unsaves (Damage Applied):
Average Wounds * (1 - P(Save))(where P(Save) is the best of Armour or Invulnerable Save after AP) - Average Damage Before FNP:
Average Unsaves * Damage per Wound - Average Total Damage:
Average Damage Before FNP * (1 - P(FNP))
Variables Table for 40k Dice Calculator
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Number of Attacks | Total dice rolled initially. | Unitless (count) | 1 - 200 |
| To Hit (BS/WS) | Required D6 roll for a hit. | X+ (target roll) | 2+ to 6+ |
| Hit Modifier | Modifier to the hit roll. | +/- (integer) | -3 to +3 |
| Re-roll Hits | Type of re-roll applied to hits. | Categorical | None, 1s, Failed |
| To Wound (S vs. T) | Required D6 roll for a wound. | X+ (target roll) | 2+ to 6+ |
| Wound Modifier | Modifier to the wound roll. | +/- (integer) | -3 to +3 |
| Re-roll Wounds | Type of re-roll applied to wounds. | Categorical | None, 1s, Failed |
| Armour Save | Opponent's base armour save. | X+ (target roll) | 2+ to 7+ (None) |
| AP Value | Armour Penetration of your weapon. | - (integer) | 0 to 6 |
| Invulnerable Save | Opponent's invulnerable save. | X+ (target roll) | None, 2+ to 6+ |
| Damage per Wound | Damage inflicted by each unsaved wound. | Unitless (count) | 1 - 100 |
| Feel No Pain (FNP) | Opponent's FNP save roll. | X+ (target roll) | None, 2+ to 6+ |
Practical Examples Using the 40k Dice Calculator
Let's illustrate the power of this 40k dice calculator with a couple of common scenarios:
Example 1: Anti-Infantry Firepower
Imagine a unit of ten Space Marines firing Boltguns at a unit of Ork Boyz.
- Inputs:
- Number of Attacks: 20 (10 Marines, 2 shots each)
- To Hit (BS/WS): 3+
- Hit Roll Modifier: 0
- Re-roll Hits: Re-roll 1s (from a nearby Captain)
- To Wound (S vs. T): 3+ (S4 Bolter vs. T5 Ork)
- Wound Roll Modifier: 0
- Re-roll Wounds: No Re-rolls
- Opponent's Armour Save: 6+ (Ork Boyz)
- AP Value: 0 (Bolter AP0)
- Invulnerable Save: None
- Damage per Successful Wound: 1
- Feel No Pain (FNP) Save: None
- Expected Results:
- Average Hits: ~14.44
- Average Wounds: ~9.63
- Average Successful Saves: ~3.21
- Average Total Damage: ~6.42
- Interpretation: On average, this unit will deal about 6-7 damage to the Ork Boyz, likely eliminating several models.
Example 2: Anti-Tank Weaponry
Consider a single Lascannon shot from a Tank Commander against an enemy Land Raider.
- Inputs:
- Number of Attacks: 1
- To Hit (BS/WS): 3+
- Hit Roll Modifier: 0
- Re-roll Hits: Re-roll Failed Hits (from Tank Commander's ability)
- To Wound (S vs. T): 3+ (S9 Lascannon vs. T12 Land Raider)
- Wound Roll Modifier: 0
- Re-roll Wounds: No Re-rolls
- Opponent's Armour Save: 2+ (Land Raider)
- AP Value: 3 (Lascannon AP-3)
- Invulnerable Save: None
- Damage per Successful Wound: D6 (average 3.5, so use 3.5)
- Feel No Pain (FNP) Save: None
- Expected Results:
- Average Hits: ~0.88
- Average Wounds: ~0.59
- Average Successful Saves: ~0.20
- Average Total Damage: ~1.36
- Interpretation: A single Lascannon shot, even with re-rolls, has a decent chance to wound but the Land Raider's strong save (reduced to 5+ by AP-3) means the average damage per shot is relatively low. This highlights why multiple anti-tank shots are often needed.
How to Use This 40k Dice Calculator
Using our 40k dice calculator is straightforward. Follow these steps to get accurate combat predictions:
- Enter Number of Attacks: Input the total number of attacks your unit makes. Remember to account for multiple shots per model, if applicable.
- Set To Hit (BS/WS) and Modifier: Choose your unit's Ballistic Skill (BS) or Weapon Skill (WS) and any modifiers to the hit roll (e.g., -1 for Heavy weapons, +1 for specific auras).
- Select Hit Re-rolls: Choose the appropriate re-roll option if your unit has abilities to re-roll 1s or all failed hit rolls.
- Set To Wound (Strength vs. Toughness) and Modifier: Determine the required roll to wound based on your weapon's Strength (S) compared to the enemy's Toughness (T). Apply any wound modifiers.
- Select Wound Re-rolls: Similar to hits, choose if your unit can re-roll 1s or all failed wound rolls.
- Enter Opponent's Armour Save and AP: Select the enemy unit's base Armour Save and input your weapon's Armour Penetration (AP) value. The calculator will automatically adjust the effective save.
- Select Opponent's Invulnerable Save: If the enemy has an Invulnerable Save, select it. This save is never modified by AP. The calculator will use the better of the two saves.
- Enter Damage per Successful Wound: Input the damage characteristic of your weapon. For D3 or D6 damage, use the average (e.g., 2 for D3, 3.5 for D6).
- Select Opponent's Feel No Pain (FNP) Save: If the enemy has a FNP ability, select the required roll.
- Click "Calculate": The results will instantly appear, showing average hits, wounds, saves, and total damage.
- Interpret Results: The primary result is the average total damage. Intermediate values show the step-by-step breakdown. Use these numbers to inform your tactical decisions and army building.
Key Factors That Affect 40k Dice Outcomes
Understanding the variables that most significantly influence combat outcomes is crucial for any Warhammer 40,000 general. A 40k dice calculator highlights these impacts:
- Number of Attacks: This is the most fundamental factor. More attacks inherently lead to more hits and wounds. Units with high attack counts, even with low individual damage, can be highly effective.
- To Hit Roll (BS/WS): A unit's inherent skill to hit. Improving a 4+ to a 3+ has a significant impact on output, especially with many attacks. Modifiers here are critical.
- Re-rolls (Especially Failed Rolls): Re-rolls are incredibly powerful. Re-rolling failed hits or wounds almost doubles the effective probability of success in that phase, often having a greater impact than a +1 modifier. Re-rolling 1s is also strong, particularly for units with many dice.
- To Wound Roll (Strength vs. Toughness): The interaction between your weapon's Strength and the enemy's Toughness dictates the difficulty of wounding. Aiming for a 2+ or 3+ wound roll drastically increases efficiency.
- Armour Penetration (AP): High AP values directly reduce the opponent's effective save, bypassing their defenses. Against heavily armored targets, AP is often more important than raw damage.
- Opponent's Saves (Armour and Invulnerable): The enemy's ability to shrug off damage. A good save (especially an Invulnerable Save that ignores AP) can drastically reduce incoming damage. Knowing the enemy's saves is vital for targeting.
- Damage Characteristic: The amount of damage per successful wound. High damage weapons are crucial for taking down multi-wound models or vehicles. Even a small increase in damage (e.g., D1 to D2) can halve the number of wounds needed to destroy a target.
- Feel No Pain (FNP): A final layer of defense that allows a model to ignore damage after it has been allocated. FNP saves are powerful because they apply to all incoming damage, regardless of AP, making high-damage weapons less efficient against such units.
Frequently Asked Questions (FAQ) about the 40k Dice Calculator
Q: Is this 40k dice calculator 100% accurate?
A: This calculator provides average statistical outcomes over a large number of dice rolls. In any single game, actual dice rolls will vary due to chance. It's a tool for predicting reliable trends, not guaranteeing exact results for one turn.
Q: Does this calculator account for critical hits or critical wounds (e.g., 6s auto-wound)?
A: The current version of this calculator focuses on the fundamental probability chain. Advanced rules like critical hits/wounds are not explicitly factored into the primary calculations, but the core probabilities still apply to the base rolls.
Q: Can I simulate multiple units or weapon profiles at once?
A: No, this calculator is designed for a single unit's attack profile against a single enemy profile. For multiple units or varied weapons, you would need to perform separate calculations and sum the results.
Q: What if my weapon has a variable damage (e.g., D3 or D6)?
A: For variable damage, it's best to input the average damage value. For D3, use 2. For D6, use 3.5. This will give you the average expected damage.
Q: Why should I use a 40k dice calculator instead of just rolling dice?
A: A calculator helps with strategic planning, list building, and understanding the true statistical efficiency of your units. It removes the emotional bias of "lucky" or "unlucky" rolls and provides a consistent baseline for comparison.
Q: What are the limitations of this 40k dice calculator?
A: This calculator does not account for complex interactions like specific stratagems, command re-rolls (beyond the general re-roll options), morale tests, unit cohesion, or specific abilities that modify rolls in unique ways (e.g., "ignore modifiers"). It focuses on the core hit-wound-save-damage sequence.
Q: Are the units for the calculator inputs adjustable?
A: For a 40k dice calculator, most inputs are unitless counts (number of attacks, damage) or target rolls (2+, 3+). The results are also unitless counts representing average outcomes. Therefore, no unit switcher is necessary as there aren't multiple measurement systems applicable.
Q: How exactly do re-rolls work in the calculation?
A: When you select 'Re-roll 1s', the calculator determines the probability of a 1 failing, and then factors in a second chance at success for those specific dice. For 'Re-roll Failed', any die that doesn't succeed on its first attempt gets a second chance, significantly boosting the overall success rate.
Related Tools and Internal Resources
Enhance your Warhammer 40,000 experience with these other helpful resources:
- Warhammer 40k Army Builder: Design and optimize your army lists.
- 40k Unit Comparison Tool: Compare the stats and abilities of different units side-by-side.
- Terrain Placement Guide 40k: Master battlefield setup for tactical advantage.
- Stratagem Efficiency Calculator: Analyze the cost-benefit of using specific stratagems.
- Match Up Win Rate Tracker: Keep track of your win rates against different factions.
- Warhammer 40k Strategy Guide: Comprehensive articles and tips for competitive play.