Damage calculator

From the launch client tooltips on the spellbook pages, rank by rank. Spell power coefficients are used where the client lists them; otherwise the Classic rule applies: cast time divided by 3.5 for direct damage and duration divided by 15 for damage over time, reduced for spells learned below level 20.

No. It is a per-ability calculator: it tells you what one cast is expected to do and what that is per second, so you can compare spells and ranks at your stats. It does not model rotations, procs, resistances by school, or buffs beyond the talent bonus field.

Weapon damage is average weapon damage plus attack power ÷ 14 × speed. Instant attacks use the normalised speed (3.3 two-hand, 2.4 one-hand, 1.7 dagger, 2.8 ranged); next-melee attacks use your real weapon speed. Melee crits deal double damage.