How the mortgage calculator works
Enter the home price, your down payment (in dollars or as a percent), the interest rate, the loan term, and your yearly property tax and insurance. The calculator finds the loan amount, works out the fixed monthly principal-and-interest payment, then adds one-twelfth of your yearly tax and insurance to give the full monthly payment.
The formula
M = P × r(1+r)^n / ((1+r)^n − 1), where P is the loan amount, r the monthly rate (annual rate ÷ 12) and n the number of monthly payments. Tax and insurance are added as yearly amount ÷ 12.
Private mortgage insurance (PMI), HOA dues and flood insurance are not included. If you put down less than 20% on a conventional loan, expect PMI on top of this figure.
Frequently asked questions
What is included in the monthly payment?
Principal, interest, and one-twelfth of the yearly property tax and homeowners insurance you enter. PMI and HOA dues are not included.
How is the loan amount calculated?
Home price minus down payment. Change the down payment in dollars or as a percent — the other updates automatically.
How much interest will I pay over the life of the loan?
The calculator shows total interest as the monthly principal-and-interest payment × number of payments − the loan amount. Open the amortization schedule to see it payment by payment.
Does a bigger down payment lower my payment?
Yes — it lowers the loan amount, and so the principal-and-interest payment and the total interest. On a conventional loan, 20% down also avoids PMI.
Results are estimates for planning, not financial advice. Last reviewed 2026-09-28.