Board Thread:Skyrim/@comment-1401879-20130614233659/@comment-2052658-20140111085712

When stacking %-bonuses from different sources there are many different ways to go. I'll try to enumerate the ones I know of, in case it helps anyone. I'll use the example of a Breton (25% magic resist) wearing a ring and an amulet of magic resistance (10% and 30% respectively): First of all I think there are three reasonable ways to choose which bonuses will stack: For the sake of example I'm assuming that we choose to stack bonuses additively, see below for other options.  Use only the most powerful bonus (no stacking) 30% resistance (best overall bonus). The ring and Breton bonuses are ignored. Allow different "types" of bonuses to stack ("category" stacking)  e.g. Dungeons and Dragons uses a system like this (well, 3.5e does). Thus casting Mage Armor does not help if you're already wearing full-plate, as they both provide an "armor" bonus.  30% (best "gear" bonus) + 25% (best "race" bonus) = 55% resistance. The ring is ignored. All bonuses stack 30% (amulet) + 10% (ring) + 25% (Breton) = 65% resistance.</li></ul></li> </ol>

Given that the game uses a system which allows multiple sources of bonuses to stack, it also needs a system to determine how they stack. For "flat" values it's almost always additive, but for percentages (as in this case) there are some options: For the sake of example I'm assuming that all bonuses stack, but see above. <ol> "Additive" stacking: Add up the bonuses and apply them all at once 30% + 25% + 10% = 65% resistance.</li></ul></li> "Multiplicative" stacking: (1) If there is a "base" value, apply the bonuses one by one to the accumulating value. (2) If the bonus is a mitigative stat, apply them one by one to the diminishing damage. The second interpretation applies.</li> If 100 magic damage would be taken, the amulet prevents 30%, then our Breton blood prevents 25% of the remaining 70, then the ring prevents 10% of the remaining 52.5. This leaves us with 47.25 damage or 52.75% magic resistance (the order does not matter, the result will be the same in any case).</li></ul></li> </ol>

From reading the pertaining articles it seems like what we're dealing with is the following:  Magic resist bonuses will stack additively, up to a cap of 85%.</li> Element resist bonuses will stack additively, up to a cap of 85%.</li> Magic absorption will stack additively, with no cap.</li> The results of all of the above will stack multiplicatively with each other.</li></ul>