How do +Dodge skills and passives stack in Diablo 3?

I have a Monk with 25% dodge if I use nothing by my Dex score. If I add a passive that gives +15% dodge, the final dodge chance only increases to 36.2; with Mantra of Evasion active (which gives another +15% dodge) the final dodge change increases to 45.8%; if Mantra of Evasion is within three seconds of being cast, than it offers another +15% which gives a final dodge change of 53.9%.

Obviously, these are not additive percentages but I am having trouble figuring out the formula involved. What is actually happening to my Dodge Change when I gain +15% Dodge? If it helps, my Monk is level 56 and currently in Hell.

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– Frank Jun 14 '12 at 3:26
@fbueckert Very similar, and possibly is a duplicate, however I personally think it isn't, it seems the other question is more asking how dodge mechanics work, not really how the equations work, while that's what this question is asking. – Mr Smooth Jun 14 '12 at 10:16

Dodge percentages multiply out. First, start by thinking of x% dodge as (100-x)% chance to be hit. Specifically, 15% dodge = 85% chance to be hit.

75% base => 25% dodge
75% base * 85% from passive = 63.75% chance to be hit => 36.25% chance to dodge
75% base * 85% from passive * 85% from mantra = 54.1875% chance to be hit => 45.8125% chance to dodge

... and so on. The dex->dodge conversion is also non-linear, but it's not the usual x / (y + x) formula.

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... yes. Yes it is. Fixed. :) – Catalept Jun 14 '12 at 2:33
Actually, you're wrong when you say that "unlike most other stats". ALL defensive stats in Diablo 3 multiply together (in %), it seems that only offensive stats do not – Mr Smooth Jun 14 '12 at 10:14
Fixed. Because of the rating-based nature of the other stats, I expected there to be effects that boosted the rating directly, but it turns out there aren't any :) – Catalept Jun 14 '12 at 21:06

Catalept answered already while I was typing this; so I'm leaving out the detailed explanation, but posting as it explains your actual scenario.

The calculation is multiplicative; so

• Base dodge: 0.25
• Guardian's Path (15%): 0.15
• Mantra of Evasion: 0.15
• Evasion first 3 secs: 0.15

would result in

(1 - 0.25)(1 - 0.15)(1 - 0.15)(1 - 0.15) = 0.75 * 0.85 * 0.85 * 0.85 = 0.46059375 ~= 0.461

So you have 46.1% chance to be hit; ie. 53.9% dodge

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