Mortgage Calculator
Estimate your monthly payment and see the full amortization schedule, total interest, and how extra payments shorten your loan.
How this mortgage calculator works
Enter your loan amount, interest rate (APR) and term. The calculator returns your fixed monthly principal-and-interest payment, the total interest you’ll pay over the life of the loan, and a month-by-month amortization schedule you can download as CSV.
Early in a fixed-rate mortgage, most of each payment is interest because interest is charged on a large remaining balance. As the balance falls, more of every payment goes to principal — which is why the “Loan balance over time” chart curves downward faster near the end. Adding even a small extra monthly payment attacks the principal directly and can cut years and tens of thousands in interest off a 30-year loan.
What’s included — and what isn’t
This tool shows principal and interest only. Your real monthly housing cost also includes property tax, homeowners insurance, and (if your down payment is under 20%) private mortgage insurance. Those vary by location and lender, so estimate them separately and add them to the payment shown above.
Frequently asked questions
How is a monthly mortgage payment calculated?
It uses the amortization formula M = P·r / (1 − (1 + r)−n), where P is the loan amount, r is the monthly rate (annual APR ÷ 12), and n is the total number of monthly payments. Interest each month is charged on the remaining balance; the rest of the payment reduces principal.
How much can extra payments save me?
Every extra dollar goes straight to principal, so it shortens the loan and removes all the future interest that principal would have generated. Type an amount into “Extra monthly payment” to see your new payoff time and the interest saved.
Does this include taxes and insurance?
No — it’s principal and interest only. Add property tax, homeowners insurance and any PMI on top for your full monthly cost.
BriskToolbox provides estimates for general information only and is not financial advice. Confirm exact figures with your lender.