Critical Hit - How to calculate it?

I know critical hit causes higher damages, but the question is how much? How to calculate it?

 

Critical hits double your melee power on most attacks. Crossbows see the basic, ie slashing or crushing damage from bolts, doubled instead.

 

Thank you. But, I don't understand what you meant with crossbows?

 

He means that exotic damages are *NOT* doubled on critical crossbow shots. Mundane being Slashing, Crushing, and Piercing in this case I believe. (It *May* include blasting, and not Piercing, but I just do not remember.)