I was wondering if I have a brand new hero.... Can anyone tell me the specs on how many levels your new hero will go down compared to the hero you are transferring..

For Example: If I had a DOM 1 hero and want to transfer that to another hero.. does the new hero ( barring using the perfect gem theory) lose 4-5 cards?? Is their a formula out there in another post that someone could direct me too.. Thank you Guy/gals...