Mortgage Calculator 🔒 Your data never leaves your browser.
Estimate mortgage payments from home price, down payment and rate.
About this tool
This mortgage calculator subtracts your down payment from the home price to get the loan amount, then runs the same amortization formula lenders use to work out a fixed monthly principal & interest (P&I) payment from that loan amount, the annual interest rate and the term in years. For example, a $400,000 home with an $80,000 down payment (20%) at 6% over 30 years gives a $320,000 loan, a payment of about $1,918.56 a month, roughly $690,682 paid in total, and about $370,682 of that being interest.
Everything updates as you type, entirely in your browser — nothing is sent anywhere. Note that this covers principal & interest only: real monthly mortgage payments usually also include property tax, homeowners insurance, and — if your down payment is under 20% of the home price — private mortgage insurance (PMI), none of which this tool estimates. Treat the numbers as a planning estimate, not a binding loan offer.
Frequently asked questions
Why does a bigger down payment lower my monthly payment by so much?
Your down payment directly reduces the loan amount that gets financed — every dollar of down payment is a dollar you never pay interest on. Because mortgage payments are calculated on the loan amount, not the home price, a larger down payment shrinks both the principal being amortized and the interest charged on it every month, which compounds over a 15-30 year term into a substantial difference.