40K Stats Calculator

Quickly estimate expected hits, wounds, failed saves, and average damage in Warhammer 40,000. Enter your attack profile, target defenses, and rerolls to see a clean breakdown plus a visual chart of each combat step.

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Expert Guide to Using a 40k Stats Calculator

A 40k stats calculator is one of the most practical tools a Warhammer 40,000 player can use when comparing units, weapons, and target profiles. In a game where outcomes are driven by dice but informed by list construction, understanding averages matters. A good calculator turns the attack sequence into a set of readable probabilities: how often attacks hit, how many of those hits wound, how many wounds get through armor, and how much damage the target is expected to take in the end. That information is invaluable when you are deciding between weapon options, identifying overkill, or trying to work out whether a target is likely to survive a key activation.

The calculator above is designed around the basic 40k attack sequence. You enter the number of attacks, the attacking model’s hit roll requirement, whether rerolls apply, the weapon’s Strength, the defender’s Toughness, the target’s armor and invulnerable saves, the weapon’s AP, and the damage characteristic. The output then gives you expected hits, expected wounds, expected failed saves, and average damage. While it does not replace full game knowledge, it gives you a fast and reliable statistical baseline for decision-making.

Why expected values matter in Warhammer 40,000

Players often describe units as “reliable” or “swingy,” but those labels are usually based on a mix of memory and intuition. A 40k stats calculator helps replace guesswork with measurable averages. If one unit is expected to deal 6.7 damage to a target and another is expected to deal 4.9, you can make cleaner comparisons. You can also identify whether buffs are worth investing in. Sometimes rerolling 1s adds a modest increase; sometimes full rerolls dramatically change the profile.

Key point: Expected value does not guarantee a result in a single game. Instead, it shows what would happen on average over many repetitions of the same attack sequence. That makes it ideal for list planning, target priority, and efficiency comparisons.

How the core 40k attack sequence is modeled

The standard attack flow in Warhammer 40,000 can be summarized in four main stages:

1. Attacks are made. The weapon profile or unit ability determines how many attack dice are rolled.
2. Hit rolls are resolved. Each attack succeeds on the weapon skill or ballistic skill threshold, such as 3+ or 4+.
3. Wound rolls are resolved. Strength is compared to Toughness to determine the wound threshold.
4. Saves are rolled. The target uses its armor save modified by AP, or its invulnerable save if that is better.
5. Damage is applied. Each unsaved wound inflicts its listed damage.

The calculator follows that sequence exactly. It uses the standard d6 success probabilities and applies rerolls at the hit and wound stages. The save stage takes AP into account and automatically chooses the better result between the modified armor save and an invulnerable save if one exists.

Understanding d6 success rates

Most core 40k rolls use a six-sided die. That makes the math transparent once you know the threshold. A 3+ succeeds on four faces of the die, so its raw probability is 4 out of 6, or 66.67%. A 4+ succeeds on three faces, or 50%. These percentages become the foundation for every expected value in the attack sequence.

Required Roll	Successful Faces on d6	Probability	Expected Successes per 10 Dice
2+	5 of 6	83.33%	8.33
3+	4 of 6	66.67%	6.67
4+	3 of 6	50.00%	5.00
5+	2 of 6	33.33%	3.33
6+	1 of 6	16.67%	1.67

Those are real, exact probabilities for a fair six-sided die. They become even more useful when you layer in rerolls. Full rerolls increase reliability much more than many players expect. For example, a raw 4+ hit rate is 50%, but with full rerolls it becomes 75%. That is because failed dice get a second chance. Reroll 1s is smaller but still meaningful, especially on large attack volumes.

How Strength versus Toughness affects wound rolls

Wounding in 40k is not based on a fixed weapon profile alone. It depends on how the attacker’s Strength compares to the defender’s Toughness. This is one of the most important breakpoints in the whole game because small shifts in Strength or Toughness can move the wound threshold by a full step.

Strength Compared to Toughness	Required Wound Roll	Probability	Common Tactical Meaning
Strength at least double Toughness	2+	83.33%	Highly efficient anti-target profile
Strength greater than Toughness	3+	66.67%	Good match into target
Strength equals Toughness	4+	50.00%	Neutral efficiency
Strength lower than Toughness but more than half	5+	33.33%	Below ideal damage profile
Strength half Toughness or less	6+	16.67%	Poor conversion without buffs

This table is why breakpoints matter so much in list design. Going from Strength 4 into Toughness 4 gives you a 4+ to wound, or 50%. If you increase to Strength 5 into that same target, the wound chance jumps to 66.67%. If you reach Strength 8 into Toughness 4, you improve again to 83.33%. The result is not linear; it moves in meaningful thresholds.

AP, armor saves, and invulnerable saves

After wounds are determined, the target attempts to save them. Standard armor saves are worsened by AP. For instance, a 3+ save hit by AP -2 becomes a 5+ armor save. If the target also has a 4+ invulnerable save, it will use the better option, which in this case is the 4+. This is why AP is especially strong against high-armor targets that do not have a strong invulnerable save, and less decisive against targets that do.

When you use the calculator, enter AP exactly as shown on the datasheet. The calculator applies the modifier to the target’s armor save and then compares it against any invulnerable save you entered. This creates a more realistic estimate than simply looking at armor alone.

How to interpret the chart

The chart generated by the calculator gives a stage-by-stage visualization of the attack sequence. It starts with total attacks and then shows the expected value after each gate in the system: hits, wounds, failed saves, and total damage. This is useful because it tells you where a weapon profile is losing efficiency.

• If the biggest drop occurs between attacks and hits, the unit needs accuracy buffs or more attacks.
• If the biggest drop occurs between hits and wounds, the Strength is poorly matched into the target’s Toughness.
• If the biggest drop occurs at the save stage, the AP may be too low for the target you are shooting.
• If failed saves are respectable but damage is still low, your damage characteristic may be insufficient for the target’s wound pool.

Practical examples of 40k stats calculator usage

Suppose you are comparing two anti-elite options. Weapon A fires 10 attacks at 3+, Strength 5, AP -1, Damage 2. Weapon B fires 6 attacks at 3+, Strength 8, AP -2, Damage 3. Against a Toughness 4 target with a 3+ armor save and no invulnerable save, Weapon B may produce fewer total hits but more efficient wounds and more unsaved damage because its Strength and AP are superior. Against a lighter target with worse armor, Weapon A could be more efficient because higher attack volume pushes more total conversions through. The calculator helps reveal which profile is better into which defensive stat line.

This matters even more when buffs are involved. A commander aura granting reroll 1s to hit often improves a high-volume unit more in total output simply because more dice benefit. Full rerolls, on the other hand, can transform lower-volume, high-value shots into much more dependable damage. If your game plan depends on destroying one vehicle, reliability can be more important than raw top-end potential.

Common mistakes players make when estimating damage

• Ignoring the wound roll breakpoint. Many players focus on AP and Damage while overlooking the fact that changing from wounding on 5+ to 4+ is a huge increase.
• Overvaluing AP into invulnerable targets. A target with a strong invulnerable save can flatten the advantage of heavy AP.
• Assuming average output equals guaranteed output. Expected value describes a mean result, not certainty in a single activation.
• Forgetting rerolls on large sample sizes. Even a small reroll benefit compounds noticeably when many dice are rolled.
• Comparing weapons without defining the target. No weapon is best in a vacuum. The target profile determines the value of Strength, AP, and Damage.

What this calculator does well and what it does not include

This calculator is built to be fast, readable, and practical for general use. It handles the standard attack chain and common reroll scenarios. It is ideal for comparing weapons and target profiles in ordinary game situations.

However, advanced 40k interactions can push beyond simple expected-value math. Examples include sustained hits, lethal hits, devastating wounds, feel no pain rolls, damage reduction, anti-keywords, critical hit mechanics, mortal wounds, blast scaling, and faction-specific modifiers. If those rules matter in your matchup, use this calculator as a baseline and then layer on the relevant special rules manually.

How to get better at list building with a 40k stats calculator

The best way to use a 40k stats calculator is not just to answer one question, but to compare several common battlefield problems. Build a quick test set for the targets you expect to face most often:

1. Light infantry, such as Toughness 3 or 4 with a 5+ or 4+ save.
2. Elite infantry, such as Toughness 4 to 6 with a 3+ save and sometimes an invulnerable save.
3. Light vehicles or monsters, often around Toughness 9 to 10.
4. Heavy vehicles or monsters, often Toughness 11 to 12 with strong saves.

Then test your roster into each category. If too many of your weapons stall at the wound step against high Toughness targets, you need more Strength. If your anti-elite tools hit and wound well but bounce off armor, you need more AP or a way to bypass saves. If your damage output is statistically solid but still leaves enemies alive, you may need better damage characteristics or more total attacks. The calculator turns abstract weapon choice into a practical roster-building process.

Why probability education matters for tabletop gaming

If you want to go deeper into the mathematics behind a 40k stats calculator, probability resources from established academic and public institutions are helpful. The attack sequence in 40k is a textbook example of repeated Bernoulli trials and conditional probability. For broader background on probability and data literacy, see the NIST Engineering Statistics Handbook, the University of Minnesota open statistics text, and the U.S. Census Bureau statistical publications. These sources are not about Warhammer specifically, but they explain the same statistical principles that make expected-value calculators useful.

Final thoughts

A strong 40k player blends rules knowledge, mission awareness, movement discipline, and statistical judgment. A 40k stats calculator supports that final piece. It helps you understand not just what a weapon can do, but what it is likely to do. Over time, that makes your target choices sharper, your list construction more balanced, and your in-game planning more realistic.

Use the calculator above as a practical benchmark whenever you are deciding between profiles, evaluating buffs, or preparing for a new meta. The goal is not to remove uncertainty from Warhammer 40,000. The goal is to make uncertainty legible, so that your decisions are driven by informed probability rather than vague instinct.