5% and a term of 30 years. You're not really paying just 4. 5% of $200,000 as interest; you're paying interest on what stays of the balance after each payment every month. Since your monthly payment is only a small fraction of the total quantity you owe, only a small part of the loan balance gets paid off, and interest gets charged again on that balance the next month.Your mortgage payment is the exact same monthly unless your interest rate changes, however the parts of your mortgage payment that goes towards your principal and interest charges alters the longer you have the home loan. Interest payments are front-loaded early on and are slowly lowered until principal payments begin to surpass them.