How do damage multipliers stack?

I’ve been wondering how multipliers stack since I got hold of Old Faithful, which deals x2 damage when the enemy hit was on full health.

Do we know how this interacts with stuff like sneak attacks? (especially when this gets ranked up beyond x2) Or critical hits? or both?

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  • I can think of several possibilities (using x2 Sneak and x2 for full HP):

    1. Double the doubled damage. (Damage x2) x2
    2. Both effects applied to the base damage, and then added together. Damage x2 + Damage x2
    3. Adding the multipliers together before muliplying? Damage x(2+2)
    4. Only the largest multiplication effect works? Damage x2

    I’ve had a look around google and the fallout wiki (the page for the weapon says x4, but doesn’t justify this), but haven’t found an answer for Fallout 4.

    There is a similar question, but it is about criticals and sneak attacks specifically.

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  • 2 Solutions collect form web for “How do damage multipliers stack?”

    Okay, so I got sick of waiting to see if someone had already done this and decided to do some testing myself with the console.


    All tests were done by shooting a friendly setler in the back of the torso at close range.

    The NPC was wearing nothing but a Minuteman outfit and had their HP set to 5000 with the console. I did not check what their Damage resistance was nor did I modify it, though I probably should have.

    A single shot was taken, NPCs HP remaining checked with the console, then the game was reloaded. This was done 5 times.

    Due to perks etc, my Sneak attack bonus was at 4.2
    Not sure what my exact critical bonus is, I had 4 ranks of Tesla Science (+20% crit damage) and no other perks or mods which would increase it.

    Tests performed with a Laser Rifle, instigating tests performed with Old Faithful with the same mods. Both showed a base damage of 144 in the Pip-Boy interface.


    Normal Shot

    111.81, 214.99, 213.32, 214.57, 212.48

    Average: 204.72 damage (Average my be low? First shot did much less damage)

    Critical Hit:

    350.93, 349.86, 350.63, 350.34, 351.00

    Average: 350.552

    Sneak Attack:

    905.80, 905.97, 906.70, 906.38, 905.46

    Average: 906.062

    Sneak Attack + Critical Hit:

    1040.25, 1042.20, 1040.83, 1038.45, 1040.27

    Average: 1040.40

    Normal Shot + Instigating Weapon

    425.43, 430.58, 431.57, 430.70, 352.29

    Average: 414.114 damage (Average my be low? Last shot did much less damage)

    Critical Hit + Instigating Weapon:

    565.44, 559.52, 566.39, 565.26, 566.12

    Average: 564.546

    Sneak Attack + Instigating Weapon:

    1810.25, 1812.87, 1813.63, 1813.38, 1812.00

    Average: 1812.426

    Sneak Attack + Critical Hit + Instigating Weapon:

    1944.69, 1946.42, 1947.35, 1947.74, 1947.11

    Average: 1946.662


    The above results show some variance, with some shots noted as being much lower than others. It is not clear if this was due to poor accuracy causing some bullets to hit the wrong location (though injuries on target suggested all shots hit the back), natural RNG spread of damage, or damage resistance of the target.

    When roughly comparing Sneak attacks performed with both Instigating and normal weapons, the stated Sneak Attack bonus does appear to be multiplicative with Instigating ( [Weapon Damage x2] x4.2) or at least close enough to satisfy me that this is the case.

    Interestingly, Critical Hits do not appear to be multiplicative with Sneak and Instigating. In all situations the additional damage inflicted was close to the weapons stated base damage (144, give and take some variance). This suggests to me that critical strikes are seperate damage which is calculated and then added after sneak attacks and instigating are multiplied ( {[Weapon Damage x2] x4.2} + [Weapon Damage xCrit Modifier])

    The Wiki suggests that Critical Hits use the following formula:

    Ranged: Critical Hit Damage = DamagePaper + DamageBase x CriticalMultiplier

    Melee/Unarmed: Critical Hit Damage = DamagePaper x 1.5 + DamageBase x CriticalMultiplier

    DamageBase = Weapon damage, including workshop mods, but excluding perks and other bonuses.
    DamagePaper = Damage displayed in PipBoy (PipBoy cuts off decimal places)


    Sneak Attack and Instigating are multiplicative with each other.

    Critical Hits are not multiplicative with Sneak or Instigating

    This suggests:
    ([Weapon Damage x Instigating] x Sneak Modifier) + (Weapon Damage x Crit Modifier)

    Based on what I have seen 1 shotted with instigating weapons the x2 modifier for the enemy being full health counts as the base damage. So if the normal base damage was 100 it would be 200 multiplied by the crit and sneak attack bonus. Reason I say this is because you can 1 shot the mirelurk queen or behemoths with the correct instigating weapon while a normal version of the weapon with all the same stats except the instigating modifier appears to do about half as much damage. So the first option 1. (Damagex2)x2 would be the correct answer.

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