For a 30 year mortgage loan with a 650 credit score your interest rate will be around 4 to 5%.
The amount of the loan you'll qualify for will depend on your income and how much money you have to give the bank for a down payment on the mortgage.
Some banks however will not give a mortgage to someone with a 650 credit score and will require a credit score of 700 or above for them to qualify you for the home mortgage.
Some banks might give you a mortgage though so you'd have to contact different banks.
If you're unable to qualify for a home mortgage with your 650 credit score then you might have someone with a 700 or above credit score help you get the home mortgage by cosigning the mortgage note with you.