From Alterreality on the WoW forums, comes a long (math-filled) post about bear tanking, with this gem for trading off +AGI, +dodge, and +defense gear:

Pre-Burning Crusade Bear Form Armor

Ever wondered what was better between AGI, Dodge, or +DEF? Well here is an equivalency to help you decide! (Armor values are the increased IN BEAR FORM)

Bear Form Damage Mitigation
StatArmor Increase
Agility (1) 12.5 Armor
Dodge (1%) 250 Armor
Defense (1) 33.3 Armor

Burning Crusade Bear Form Armor

Reclaculated for BC stats (24k Bear armor, and 23% dodge). It's important to note that the formulas change with changes in Dodge and Armor

Burning Crusade Bear Form Armor
StatArmor Increase
Agility (1) 34.18 Armor
Dodge (1%) 466.52 Armor
Dodge Rating (1) 24.4925
Defense (1) 37.32 Armor

Armor Stat Weights

If you are comparing armor while buying on the AH, you want to compare the armor specs, so here are the trade-offs:

Stat Effects on Base Armor
StatBase Armor Increase
Agility (1)2.7
Dodge (1%)54
Def (1)7.2

where equals ('=') means 'roughly equivalent to' while tanking in bear (Thank you to Galliard for the idea to express in this manner)

Using a weighting system (like the one found on, weight should be applied as follows:

Armor Weighting System Stat Weights
Dodge Rating4.05
Def Rating2.6

To calculate an items full "Armor" value:

(AGI * 2) + (+Def * 33.3) + (Dodge * 250) + (Armor * Armor_Modifier) = Final Armor Value 
  • This is the emulated ARMOR VALUE something like the "tank point".

Agility, Enchantment and leather working is influenced by nether the "bear armor fact" nor thick hide talent; Armor from gear is influenced by both; The Mark of Wild is influenced by only thick hide talent

(Note that by "bear form" here, the poster clearly meant Dire Bear Form.)

Damage Mitigation Mechanics

Let's move into a more in-depth discussion of just how these numbers work.

First we assume the mob we are facing is lvl 73. The armor vs reduction formula can be found at damage reduction. Let's re-paste it here (Simplified for a 73 mob):

Reduction = (Armor / (Armor + 11960))
    (NOTE: No need for a % value)

Dodge (and Miss) reduces total damage by:

Reduction = Dodge/100

However, Dodge and Armor reduction have multiplicative diminishing returns, meaning that the total reduction from both is:

Tot Reduction = (1 - (Armor / (Armor + 11960)) * (1 - Dodge/100)

Unfortunately, the fact that both Armor and Dodge are in this formula makes it mildly worthless. To counteract this we will look for the amount of Total Reduction we get out of 1 point of Armor or Dodge at any respective value of the other stat. In otherwords, we want to know how much increasing armor by 1 point when we have X% dodge would increase our Reduction. To do this we take the derivative in respects to both Dodge and Armor. In doing so we get:

Delta Reduction by Armor = 119.6(D - 100)/(A + 11960)^2
Delta Reduction by Dodge = -119.6/(A + 11960)
      NOTE: A = Armor; D = Dodge

Note that the linear Reduction of Dodge removes Dodge from the Dodge reduction formula. Now we have the relative Deta increases of Armor and Dodge, across all ranges of Dodge and Armor. From this we can get an Armor vs Dodge ratio by dividing the two formulas. It looks like this:

Armor/Dodge Ratio = -119.6/(A + 11960) / 119.6(D - 100)/(A + 11960)^2
                  = -(A + 11960)/(D - 100)
                       NOTE: This curve is linear in respects to Armor, but exponential in respects to Dodge

Assuming the afore mentioned stats apply (24k Armor and 23 Dodge) then:

1 Dodge = 466.524 BEAR Armor

Once you have this number the rest of the conversions are easy. The only hich being that the AGI:Dodge ratio I used was very loosely based on rather inaccurate looking data I gathered myself.

Community content is available under CC-BY-SA unless otherwise noted.