Talk:Life steal/@comment-24918586-20140508193139/@comment-24513712-20140515200859

Percentage of AD. If you have 100 AD, your target has no armor, and you have 10 % life steal you will heal 10 HP for every hit to that target (100*10%=10).

If your target were to have armor, let's say 100 armor for easy calculation, you will only heal from the actual damage you deal. 100 armor blocks excactly 50 % of the incoming ad. Let's say that you again have 100 AD and 10 % life steal. When you shoot at the target you will do 50 damage (because his 100 armor blocks 50% of the incoming damage (100*50%=50). Because you have 10% life steal you will heal 5 HP for each hit (50*10%=5).

I hope that answered your question (and more)