Does Physical Resistance and Armor stack?

[Jersovic]

Like if your Physical Resistance says it reduces damage taken by 77.2%, and your armor says it reduces physical damage taken by 72%, do both of these damage reducers stack together?

[PowerGamez]

I'm not 100% sure on this but they don't stack they're multiplicative.

A few things i've read think the damage reduction formula is

Incoming Raw Damage * (1-damage reduction from armor) * (1 - damage reduction from armor) = actual damage received

E.G. you have 70% reduction from armor and 40% reduction from resist

20K raw damage * (1-0.7) * (1-0.4) = 3.6K hit taken

However I think there may be more factors in the formula

[BLSTMASTER]

I'm pretty sure its multiplicative, as it is with most other defensive stats.

Note though, it shows up as Reduces all damage from enemies of the same level as you by X %.
Inferno monsters are 61~64 so we'd need a 'new' calculation

[aggixx]

I'm pretty sure its multiplicative, as it is with most other defensive stats.

Note though, it shows up as Reduces all damage from enemies of the same level as you by X %.
Inferno monsters are 61~64 so we'd need a 'new' calculation

61-63, but the difference between damage reduction on a 60 monster and a 63 monster isn't all that significant so I wouldn't worry about it.

And the formula PowerGamez gave is correct:

total damage reduction = (1-damage reduction1)*(1-damage reduction2)*(1-damage reduction3)..... for however many different sources of mitigation you have.

[UnderworldSoup]

It's multiplicative like most of Blizzard's percentage based damage reductions in recent games. PowerGamez hit the nail on the head.

[Splatter]

Like if your Physical Resistance says it reduces damage taken by 77.2%, and your armor says it reduces physical damage taken by 72%, do both of these damage reducers stack together?

One thing to note is armor reduces all damage taken. Not just physical.

[Rife]

As said above:
It does stack, multiplicatively.

Effective Health:

- 1 resist is worth almost exactly 10 armour
- 10 int is therefor worth 10 armour
- Dont stack one at the expense of the other
- Both get better and better the more you have and if theyre roughly equivilent
- There are no diminshing returns on resistance or armour

[BLSTMASTER]

61-63, but the difference between damage reduction on a 60 monster and a 63 monster isn't all that significant so I wouldn't worry about it.

Oh I thought it would be
Act 1 :61
2: 62
3: 63
4: 64 and such >.>

Anyways, if the difference isnt that significant then I guess the calculation is still applicable.

[PowerGamez]

As said above:
- Dont stack one at the expense of the other
- Both get better and better the more you have and if theyre roughly equivilent
- There are no diminshing returns on resistance or armour

No DR but they do scale exponentially so it's good to have a mix of both. You can't just stack Resist and have no armor and vice versa. They don't get better and better the more you have, they actually get worse because it's an inverse relationship.

[Deleted]

your armor says it reduces physical damage taken

No it doesn't.

[aggixx]

Oh I thought it would be
Act 1 :61
2: 62
3: 63
4: 64 and such >.>

Anyways, if the difference isnt that significant then I guess the calculation is still applicable.

Acts III and IV (and also pony level) are both level 63 mobs, which is also the same reason why they drop the same loot.

[Ferocity]

Note though, it shows up as Reduces all damage from enemies of the same level as you by X %.
Inferno monsters are 61~64 so we'd need a 'new' calculation

Difference is not that much big. To calculate damage reduction from Armor against different level mob:

DR(Armor) = Armor / (Armor + 50*MobLevel).

Damage Reduction from Resistances against different level mob:

DR (Resistance) = RES / (RES + 50*MobLevel),
where RES = Intellect + (Resist from gear)*10

Resistance isn't shown on Char sheet precisely, it doesn't show decimal part (contribution from Int).

[Rife]

No DR but they do scale exponentially so it's good to have a mix of both. You can't just stack Resist and have no armor and vice versa. They don't get better and better the more you have, they actually get worse because it's an inverse relationship.

To clarify:

The more armour you have, the better resistance becomes in raising the raw damage needed to kill you (effective health).
The more resistance you have, the better armour becomes in increasing your effective health.
Going from 50% damage reduction to 60% damage reduction is SIGNIFICANTLY more damage reduction that going from 0% to 10%. This is what I was meaning by scaling better the more you have.
You will always gain a larger increase is effective health from raising the lower out of armour or resistance when looking at a 10:1 armour to resistance ratio.

All this being said though; Resistance is MUCH better simply because there is always more of it available on gear. The highest armour peices in the game (sans sheilds) will have ~600 armour including armour bonus stat while you can get gear with +80 resistance to all which is effectively 800 armour plus the innate armour on the item.
You can buy chest/legs etc with literally as much mitigation as a shield if you pick very high +resist all. The only difference being block chance.

[Jersovic]

lol, okay you guys, I appreciate all of the well thought responses but I'm really bad at math. I failed remedial math at the community college (while actually trying) to put in in perspective. The formulas confuse me? So if my armor says it reduces 72% of damage taken, does that mean 28% that got through also gets reduced by the Physical Resistance (77.2%)? I'm just trying to figure out how important Physical Resistance is if your armor is already high, and if one cancels the other out?

[guanqi]

in simple terms, assume its 100k incoming damage and you have 50% from armor and 50% from resist. the raw damage goes through the armor check first, come out at 50K damage then goes through the resist check and come out again at 25k. that is the damage you receive

[Cludo]

Watch this video for simple explanation!

[battledude]

It's multiplicative like most of Blizzard's percentage based damage reductions in recent games. PowerGamez hit the nail on the head.

I'm with this guy.