A mortgage calculator estimates your monthly home-loan payment from four numbers: the home price, your down payment, the interest rate, and the loan term. Enter those values and it shows exactly what you will pay each month, split into principal and interest, plus the total cost of the loan over its full life.
This free online tool is built for home buyers comparing loan offers, refinancers testing new rates, and anyone budgeting for a purchase before talking to a lender. Type in the asking price of the home, subtract what you plan to put down, and adjust the rate and term to see how each choice moves your payment. A half-point change in the interest rate or five extra years on the term can shift your monthly payment by hundreds of dollars, and the calculator makes that trade-off visible instantly. The result breaks your payment into its two parts — the principal that pays down your balance and the interest that goes to the lender — and shows the full amortization picture: total paid and total interest across all scheduled payments. There is no sign-up, no saved data, and no cost; every calculation runs in your browser the moment you change a number.
Worked example
Inputs: home price $400,000, down payment 20% ($80,000), interest rate 6.5% annual, loan term 30 years. Loan principal: $320,000. Monthly payment ≈ $2,022.62. Total paid over 30 years: $728,142.36. Total interest: $728,142.36 − 320,000 = $408,142.36. In month one, $1,733.33 of the payment is interest and only $289.29 reduces the principal.
M = 320,000 × 0.00541667 × 6.9918 ÷ (6.9918 − 1) ≈ $2,022.62 per month.
How to use it
- Enter the Home price — the purchase price of the property.
- Enter the Down payment — the amount you will pay upfront (as dollars).
- Enter the Interest rate — the annual rate quoted by the lender, as a percent.
- Select the Loan term — the repayment period in years (commonly 15 or 30).
- Read your result: the monthly payment, the principal-vs-interest split, and the total interest over the life of the loan.
The formula behind it
Frequently asked questions
How is a monthly mortgage payment calculated?
It is calculated with the fixed-rate amortization formula M = P × r × (1 + r)^n / ((1 + r)^n − 1), where P is the loan amount, r is the monthly interest rate, and n is the number of payments.
Does this mortgage calculator include property taxes and insurance?
No. This tool calculates principal and interest only — the core loan payment. Property taxes, homeowner's insurance, and HOA dues are separate costs that vary by location.
How much down payment do I need for a mortgage?
Conventional loans commonly require 3% to 20% down, and 20% usually avoids private mortgage insurance (PMI). A larger down payment lowers the loan amount, monthly payment, and total interest.
What is the difference between the interest rate and the APR?
The interest rate is what the lender charges on the balance each year. The APR folds in lender fees and points, so it is usually slightly higher — compare APRs when shopping lenders.
Can I use this calculator for a 15-year mortgage?
Yes. Select a 15-year term and the same formula applies with 180 payments — the monthly payment rises but total interest falls sharply.