A tabletop damage calculator computes exact probability distributions for multi-step attack sequences in Warhammer 40K, Age of Sigmar, and similar games. Enter attacks, hit threshold, wound threshold, save, and damage to see expected output, kill probability, and the Gamble vs. Guarantee range.
Stage-by-Stage Breakdown
| Stage | Input | Prob Each | Expected Out | 10th %ile | 90th %ile |
|---|
Wargaming Dice Gear
If you're rolling 40 attacks at once, standard board game dice won't cut it. To execute your hyper-optimized strategies efficiently, you need a high-quality bulk dice set. We recommend grabbing a brick of 36 Chessex 12mm D6s. Their smaller size allows you to roll massive handfuls without scattering them off the table. Furthermore, to protect your models and roll quietly during long tournament days, always use a dedicated neoprene dice tray.
How to Calculate Tabletop Damage
In games like Warhammer 40,000, calculating expected damage isn't as simple as multiplying the number of attacks by the flat probability of each roll. If a squad shoots 20 times, hitting on 3+, wounding on 4+, against a 5+ armor save, the outcome is a multi-step "attrition waterfall." Because dice rolls are discrete events, the variance at the beginning of the attack sequence drastically affects the end result. DiceDecay doesn't just give you an "average" damage number; it runs a full hypergeometric probability distribution. This reveals the actual shape of the bell curve, allowing you to see your 90th percentile "Spike" damage, and more importantly, your 10th percentile "Guarantee" damage floor. Stop relying on averages and start playing the odds you can actually count on.
Frequently Asked Questions
What is hypergeometric probability in Warhammer?
Hypergeometric probability calculates the exact chance of getting a specific number of successes (hits, wounds, saves) from a finite pool of dice without replacement. Unlike binomial probability (which assumes independent rolls), it accounts for the 4-stage attrition pipeline in Warhammer: Attacks → Hits → Wounds → Unsaved Damage.
What does the 'Gamble' vs 'Guarantee' metric mean?
The Gamble number is the maximum expected damage (top 10th percentile — what happens when you roll hot). The Guarantee number is the minimum expected damage (bottom 10th percentile — what happens when you roll cold). The difference between them tells you how swingy a unit's output is. Low-attack, high-quality units have narrow Gamble-Guarantee ranges.
How do reroll mechanics affect expected damage?
Rerolling 1s to hit increases expected hits by approximately 16.7% (1/6 of failures become successes). Full hit rerolls (reroll all failures) increase hits by roughly 33% for BS3+ and 50% for BS4+. The impact is multiplicative through the attrition pipeline — a 33% hit improvement can translate to 33% more wounds and 33% more unsaved damage.