Mortgages are amortizing loans, meaning: A portion of your monthly mortgage payment reduces your loan principal, and the remainder is an interest charge. For fixed-rate mortgages, the monthly payments remain the same throughout the loan term. The monthly amount may change if you have an adjustable-rate mortgage. The payment principal and interest proportions vary over time. In the first few years, payments overwhelmingly consist of interest charges, but, eventually, principal payments predominate. Your mortgage documents will include an amortization schedule specifying each payment’s principal and interest amounts. The mortgage principal equals the home’s purchase price (plus any fees rolled into the loan) minus your down payment. For example, suppose you purchase a home for $380,000 and put down 20% ($76,000). If you take out a 30-year, fixed-rate loan for $304,000 with a 5% interest rate: Your monthly payment will be $1,631.94, plus any escrow amounts (for property taxes, homeowners association fees, homeowners insurance, etc.). Your total mortgage interest will be $283,497.58 if you pay off the mortgage in 30 years (i.e. 360 payments). Your total mortgage payments will be $587,497.58, almost double the original loan principal.