Armor

The Armor reduces the damage a champion receives from physical attacks. It reduces the damage of incoming physical attacks by a percentage. You can either gain Armor by Runes, Masteries, some champion's abilities or Items you buy.

A graph of damage reduction (y) against total armor (x)

Calculation
This percentage of reduction is determined by the formula: Damage Reduction = Total Armor / (100 + Total Armor). For example, a champion with 150 points of Armor would receive 150 / (100 + 150) = 60% reduced damage from physical attacks. The Total Armor is determined by your personal Armor - the amount of Armor Penetration the attacking opponent has.

Updates
Due to recent updates this article might not be actual. It was last updated during Patch 1.0.0.85. If there is a new version out, please check the data frequently.