Item power and damage
Pick your gear, quality and spec. See your item power, how much harder you hit with each upgrade, what it costs on Americas, and cheaper gear with the same power.
Every stat grows by a fixed factor for each 100 item power: +9.18% damage and healing for two-handed weapons (+8.25% for one-handed), +6% health and +3% resists. The factors come from the game's own item power table; exact ability numbers also depend on the ability itself. Spec counts 2 IP per level on that exact item, multiplied up on T5 to T8 gear; mastery and other specs in the same line add a little more that isn't counted here.
Prices are the cheapest normal-quality listing seen in the last 24 hours. Higher qualities cost more. The gearing guide explains item power in more detail.