I just bought a dell inspiron 15 laptop. It has 4gb of ram. My previous laptop was a hp 650. Will the hp ram be compatible with the dell. I want to add more ram to the dell taken from the hp.

open both systems and compare the physical look of both rams. if they are the same, it will work....

Ok. I will check. I expect them to be of the same size. because ram is one of the few easier to replace or top up components of laptops.