# What is the formula for armor/magic resist reduction?

As far as I can tell, it's something like this:

``````damage reduction = armor / (armor + 100)
``````

Is this accurate?

Yes, that's correct. The calculations are:

Armour Resist: Damage Reduction = Total Armor / (100 + Total Armor)

Magic Resist: Damage Reduction = Total Magic Resistance / (100 + Total Magic Resistance)

• And despite what it might seem, Armor does not have diminishing returns. Aug 16, 2010 at 22:36
• @Raven: That's true, but it's important to remember that a lot of armor is not better than a mix of armor/hp. Because armor boosts your survivability by a percentage of your hp, and most hp items give a flat hp boost, it's often better to buy hp once you have significant armor. I'm sure you already know this, I'm just leaving it here for any other readers. Aug 19, 2010 at 17:04
• @Raven Dreamer I would love for you to explain how Armor doesn't have diminishing returns. As is clearly stated in the formula, it does have diminishing returns. A diminishing return means that the more armor you add the less damage is reduced for each point of armor. Nov 3, 2010 at 19:47
• @Steven Oxley -- you're looking at it from the wrong perspective. While the amount of armor required per point of %damage reduction does increase (the diminishing returns you're seeing), the effectiveness per point of armor doesn't decrease. I'd open a new question if you'd like to know more -- comments aren't really suited to the indepth explanation a fuller answer would require. Please don't condescendingly assume I don't know what "Diminishing Returns" mean. Nov 3, 2010 at 19:54
• @Raven Dreamer gaming.stackexchange.com/questions/10244/… Explain away. I didn't mean to be condescending. I was just making sure we had a definition of "Diminishing Returns" to work off of. Nov 4, 2010 at 16:24

When it comes to reduction It is indeed diminishing, but when You work out the formula for Ehp (Estimated hp) 1 point of armor actually always gives 1 additional % of hp based on the base hp.

• EHP is 'effective HP', i.e. the amount of damage you can soak up. Jun 12, 2012 at 3:45