Armor and Damage Reduction Calculations

[mindbullets]

Hello, everyone. I've done some testing on the Armor calculations, and I'd like to share the results.

First off, let's look at what Armor does for the player. Armor is a stat that reduces the damage of incoming physical attacks from enemies. The exact amount of this damage reduction depends on a few things: the amount of Armor the player has equipped through gear, abilities, and talents, as well as the level of the player and the level of the attacking enemy. I found a formula available online for the physical damage reduction calculation for level 60 players here: http://wowwiki.wikia.com/Armor. However, after testing this formula as compared to the paper doll stats in the game client, I have come to conclude that the formula provided on this page is not correct. It appears that on Nostalrius Begins, the "59" in this formula is instead "60". That is:

DamageReduction = Armor / (Armor + 400 + 85 * (AttackerLevel + 4.5 * (AttackerLevel - 60)))

This matches the paper doll values at player level 60. The variable DamageReduction is a decimal number, such as .603, meaning of course 60.3% physical damage reduction. The Armor cap is widely reported to be 75% damage reduction (I have no confirmation of this, only old forum posts). Against a level 63 mob (i.e. a raid boss) this gives an Armor cap of 20708. However, given limited data about how the damage reduction scales with enemy level, it is still difficult to say for certain if this formula works for enemy level 63. Use at your own risk.

Now, onto how Armor is applied from gear, abilities and talents. Since I play a feral tank, this was written with feral druid in mind.

A feral druid gains a few Armor multipliers from his abilities and talents. Among these are:

Dire Bear Form: +360% Armor contribution from items
Bear Form: +180% Armor contribution from items
Thick Hide 5/5: 10% additional Armor contribution from items

I'd like to distinguish at this point between Base Armor and Bonus Armor. Base Armor is the white Armor value that appears on an item's stats. Bonus Armor refers to Armor from any other source, such as Agility, Mark of the Wild, Elixir of Superior Defense, the Shadowcraft 2 piece set bonus, and others. All Base Armor receives the above multipliers for Dire Bear Form and Thick Hide, while all Bonus Armor does not; the latter is simply added after the multipliers are applied. Therefore, for bear druids, 1 Base Armor = (100% + 360%)*1.1 = 4.6*1.1 = 5.06 Bonus Armor in terms of mitigation provided.

The correct Armor formula for Dire Bear Form with 5/5 Thick Hide at level 60 is:

Armor = 4.6*1.1*(Base Armor) + 2*(Agility) + (Other Bonuses) + 110

Since this formula works perfectly for Dire Bear Form, I will conjecture that the following formula works for everyone:

Armor = (Multipliers)*(Base Armor) + 2*(Agility) + (Other Bonuses) + (Armor value with no gear equipped)



If you have any corrections or comments, feel free to post below. I will make changes to this post as necessary.

[The Shortest Path]

This is really useful, thanks for running the calculations. Being able to math out armor is super important for tanks.