Possibly unpopular opinion coming up, but I would evaluate the new employer primarily based on opportunity, potential, location, flexibility, culture, and so many other things as long as they were in the general ballpark of your current salary. Granted, I hear that switching jobs/employers is an opportunity for pay bump.
But for leveraging purposes, then yeah, I'd calculate that in. (As in - "I'm currently compensated at $X, can you match that?" type of conversation, where X is 110%.) You could get super detailed and calculate the total value including all the benefits (health insurance? PTO?) and then compare it to the new place...but. *shrug* I wouldn't worry too much about the minutiae if you otherwise like the job offer.
Then again, my opinion is slightly colored by the fact that I currently hate where I work.