If you typed math hammer into Google expecting something about construction or fractions, you’re not alone, and the mix-up is easy to explain. The term has been almost entirely claimed by the tabletop gaming world. MathHammer is what Warhammer 40,000 players call the habit of running the numbers on their army before the dice ever hit the table.
There is a genuinely different product called HammerMath, an educational program built around fractions for construction trades, and if that’s what you were after, this isn’t it. Everything below covers the Warhammer 40K sense of the word, since that’s what almost everyone typing this phrase is actually looking for.
What Is Math Hammer in Warhammer 40K?
Math hammer is the process of calculating, on average, how much damage a weapon or unit is likely to deal against a given target. You take a model’s stats, things like Ballistic Skill, Strength, Toughness, and the target’s Save characteristic, and work through them step by step to land on a number.
It’s not a prediction of what will happen on turn three of your next game. It’s closer to what a poker player does when they work out pot odds. Nobody’s claiming certainty. You’re just making a better decision by understanding the range of outcomes and where the average sits inside it.
The name is a straightforward mashup, math plus Warhammer, and it stuck partly because the 40K community has always had a soft spot for turning a game about painted plastic soldiers into something you can argue about with a spreadsheet open.
Why 11th Edition Matters for MathHammer
Warhammer 40,000 moved into 11th Edition in 2026, with new Core Rules landing that June and Munitorum Field Manual updates following on a monthly cadence, including one in August. You can check Games Workshop’s official Warhammer 40,000 downloads page for the current rules and the latest points update before running any comparison. That matters more here than almost anywhere else in the hobby, because MathHammer only produces good answers when the inputs are current.
Running the numbers is also just a form of structured problem solving. It’s the same underlying instinct behind dice-based games like dice baseball, where the roll decides the outcome but knowing the odds still shapes every call you make before you throw.
Points costs shift between updates. Weapon profiles get adjusted. Abilities get rewritten or removed entirely, and defensive mechanics like invulnerable saves and Feel No Pain can change how a unit performs against the exact same attack it faced last season. Feed a calculator last year’s points value or an old ability text and the output looks precise while being quietly wrong. A guide still built around 10th Edition math, even a good one, is working from numbers that may no longer hold up.
How to MathHammer in Warhammer 40K
Here’s the actual workflow, broken into steps you can run by hand or feed into a calculator.
Step 1: Count the attacks. Start with however many shots or melee swings the weapon or unit generates.
Step 2: Calculate expected hits. Multiply the attack count by the probability of hitting. A 3+ to hit succeeds two-thirds of the time.
Step 3: Calculate expected wounds. Multiply the hits by the wound probability. A 4+ to wound succeeds half the time.
Step 4: Apply saves. Multiply by the chance the save fails. A 5+ save only succeeds a third of the time, so it fails two-thirds of the time.
Step 5: Calculate damage. Multiply the unsaved wounds by the weapon’s damage characteristic.
Step 6: Account for special rules. Rerolls, Lethal Hits, Sustained Hits, and similar abilities all adjust the numbers above before you land on a final figure.
That six-step chain is the entire engine behind every math hammer calculator you’ll ever open. The tools just automate it and often run it thousands of times as a simulation instead of one flat calculation.
A Simple MathHammer Example
Say a unit fires 10 attacks, hitting on a 3+, wounding on a 4+, against a target with a 5+ save, and each wound deals 1 damage.
10 attacks × 2/3 hit chance × 1/2 wound chance × 2/3 failed-save chance = 2.22 expected unsaved wounds
2.22 unsaved wounds × 1 damage = 2.22 expected damage
That’s the whole calculation laid out with an actual formula you can reuse on your own weapon profiles, just swap in the relevant probabilities.
Expected Damage vs Expected Kills
This distinction gets skipped constantly, and it’s one of the more useful things to understand once you’ve got the basic math down. Damage and models killed are not the same measurement.
Doing 8 damage to a 10-model squad with 1 wound each removes 8 models. Doing 8 damage to a single tough model that has 12 wounds removes nothing at all, because the unit survives with 4 wounds remaining. A weapon that averages higher damage isn’t automatically the better pick if that damage doesn’t line up with how wounds are distributed on the target.
This is where target selection actually happens. Comparing two weapons purely on expected damage misses the question that matters more in a real game: what does that damage actually remove from the board?
Average Damage Isn’t Everything
It’s an easy mistake to make, because an expected value looks far more precise than any single dice roll really is. Two units can both average 2.22 damage and feel completely different at the table. One might land reliably between 1 and 3 damage almost every turn. The other might whiff half the time and spike to 6 the other half. Same average, very different variance, and that variance matters depending on whether your list needs consistency or needs a big swing to break through a tough save.
The better calculators show a full damage distribution instead of a single number, which is exactly why that distinction matters when you’re picking one over the other.
What Is a MathHammer Calculator?
A calculator automates the six-step process above, usually letting you set up both an attacker and a defender profile with modifiers like rerolls, cover, and special abilities already built in.
Some tools use pure mathematical probability, solving the chain of percentages directly. Others run Monte Carlo simulation, meaning the software virtually rolls the dice thousands of times and reports what actually happened across every simulated attempt. Both land on similar averages, but simulation is better at surfacing the swingy, high-variance matchups a flat average would hide.
Best MathHammer Calculators and Apps
A few named tools cover most of what people search for here.
MathHammer.io is a browser-based combat calculator built around attacker and defender profiles, with support for current 11th Edition rules alongside older 10th Edition math for anyone finishing out a legacy campaign or army list.
UnitCrunch leans harder into the simulation side, running large numbers of combat rounds and showing full damage distributions rather than a single average, with support for custom modifiers and saved unit profiles.
Tabletop Calculator covers both shooting and melee, with hit modifiers, wound modifiers, cover, and invulnerable saves built in, which makes it useful for comparing several unit matchups back to back.
On the app side, mobile options exist that handle multiple weapon profiles per attacker and the full range of special rules, including Lethal Hits, Sustained Hits, Devastating Wounds, Blast, and Anti-X, which is handy for checking numbers during army list building or between turns at the table.
Can You Use Excel for MathHammer?
You can, and some players genuinely prefer it. A spreadsheet can model attacks, hit probability, wound probability, save probability, and damage across as many columns as you want, and it’s easy to build once you understand the six-step chain above.
The tradeoff shows up once special rules enter the picture. Modeling Sustained Hits, Devastating Wounds, or a stacked reroll interaction in Excel means writing increasingly nested formulas, and it’s easy to introduce a small error that skews the whole result. Dedicated calculators already have those interactions built and tested, which is why most players use Excel for simple comparisons and switch to a calculator once the rules get complicated.
How Special Rules Affect MathHammer
Modifiers change the math meaningfully, not just marginally.
A single reroll on hits or wounds pushes expected damage up more than most players estimate before they run the numbers. Lethal Hits let a critical hit skip the wound roll entirely. Sustained Hits generate extra hits on a critical result. Devastating Wounds skip the save roll on a critical wound. Anti-X abilities improve wound rolls against specific target types. Twin-linked lets you reroll wound rolls. Feel No Pain gives the defender a chance to ignore damage after saves are already resolved.
None of these need a full rules explanation here, but leaving any of them out of a comparison will make a weaker option look artificially competitive against a stronger one.
MathHammer Age of Sigmar
Age of Sigmar has its own math hammer culture, built around that game’s different wound and save mechanics. Dedicated AoS calculators exist specifically for that ruleset rather than reusing 40K formulas, since the resolution steps aren’t identical.
MathHammer Old World
The Old World deserves its own treatment too. Rank-and-flank combat resolves differently enough from 40K’s model-by-model system that borrowing 40K math will give you the wrong answer. Treat it as a separate calculation from the start.
MathHammer Kill Team
Kill Team operates at a smaller scale, individual operatives rather than full squads, so calculators built for it focus on single attack sequences and one-on-one comparisons instead of unit-wide averages.
How MathHammer Helps With Army List Building
Before spending points on a unit, math hammer lets you compare it against alternatives doing a similar job. Is a heavy weapon squad actually earning its points against a 3+ save target, or would a different loadout do more work for the same cost? Running that comparison before list submission catches weak choices before they cost you a game.
How to Compare Weapons With MathHammer
Comparing two weapons on a single target profile is a common shortcut, and it’s a misleading one. A weapon that looks excellent against a 3+ save might do very little against a 2+ invulnerable save. Run the comparison against two or three representative target profiles, not just one, before deciding which option earns a slot in your list.
What MathHammer Cannot Tell You
MathHammer estimates combat outcomes, and that’s genuinely useful, but it doesn’t account for positioning, terrain, objectives, movement, mission rules, screening, sequencing, board control, or the value of keeping a unit in reserve for a later turn. It also can’t account for your opponent’s mistakes, or your own. Treating a calculator’s output as the single deciding factor in list building skips over most of what actually wins games. It’s one input among several, not a verdict.
Common MathHammer Mistakes
A few habits show up again and again. Treating an average as guaranteed is the big one, already covered above, but it’s worth repeating because it’s the root of most “the math said this would work” frustration after a bad dice session. Forgetting rerolls is another, since a single reroll shifts expected damage more than people assume. Comparing a weapon against only one target profile hides how it performs against anything else. And leaning on rules from a previous edition after points or profiles have changed will quietly throw off every comparison built on top of it.
Frequently Asked Questions
What does math hammer mean?
Math hammer is the practice of using probability to estimate how weapons, units, and attacks perform in tabletop wargames, most often Warhammer 40,000.
How do you MathHammer?
Count the attacks, calculate the chance to hit, the chance to wound, the chance the save fails, then multiply by damage, adjusting for any special rules along the way.
What is math hammer in Warhammer 40K?
It’s the standard way 40K players evaluate whether a unit or weapon is worth its points, by working out expected damage against representative target profiles.
What is a MathHammer calculator?
A tool that automates the hit, wound, save, and damage chain, usually letting you set an attacker and defender profile and get an instant result.
Is MathHammer accurate?
It’s accurate as a statistical average across many attempts, not as a prediction of a single dice roll.
Does MathHammer work for 11th Edition?
Yes, provided the calculator or profile data has been updated to current points and rules, since older 10th Edition figures may no longer apply.
What is the best MathHammer calculator?
It depends on what you need. MathHammer.io suits quick single comparisons, UnitCrunch suits full distribution analysis, and Tabletop Calculator suits broader matchup coverage.
What is the best MathHammer app?
Mobile apps that support multiple weapon profiles and current special rules tend to be the most useful for checking numbers during list building or between games.
What is MathHammer AoS?
The Age of Sigmar version of the same practice, built around that game’s wound and save mechanics rather than 40K’s.
Can MathHammer predict who wins a game?
No. It can show which unit or weapon is statistically stronger in a specific matchup, but positioning, objectives, and in-game decisions decide actual games.
This kind of number crunching sits comfortably alongside tabletop gaming’s much older traditions too, the same lineage covered in this look at popular board games with centuries of history behind them. MathHammer is a modern layer on a habit that’s been part of tabletop play for a very long time.
Final Thoughts
Math hammer isn’t about turning Warhammer 40K into a spreadsheet exercise, even though a calculator full of hit rolls and modifiers can feel that way at first glance. It’s a way to make more informed choices with the same dice everyone else is rolling. Learn the six-step chain once, lean on a calculator once the special rules stack up, and keep your inputs current with whatever edition update just landed. That’s what separates list building based on guesswork from list building based on evidence.
