Mortgage Payment Calculator
Estimate a monthly mortgage payment before you even talk to a lender, based on the home price and what you can put down.
Last updated: August 5, 2026
How mortgage payments are calculated
When you borrow money to buy a home, you do not pay the loan back in a simple way. Each month you pay a fixed amount, and that payment is split between two parts: interest on the money you still owe, and principal that reduces the loan. Early on, most of the payment goes to interest; over time, more goes to principal.
This uses the standard fixed-rate amortisation formula. The loan amount is the home price minus your down payment, and the total interest is simply every monthly payment added together, minus the amount you borrowed.
Property tax and insurance are shown separately because they vary widely by location and are usually collected into the monthly payment with the loan. Lenders may also charge mortgage insurance if your down payment is small.
The formula
- L — loan amount (price − down payment)
- r — monthly interest rate (annual ÷ 12, as a decimal)
- n — number of monthly payments (term in years × 12)
Worked example
Home price $400,000, down payment $80,000, so the loan is $320,000 at 6.5% over 30 years.
Monthly principal + interest ≈ $2,022.62. Over 30 years you repay about $728,144, of which $408,144 is interest.
Try a 15-year term with the same fields and watch the payment rise while the total interest falls sharply — the trade-off most buyers weigh.
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Frequently asked questions
How much can I realistically afford?
A common guide is that your total monthly housing cost stays under about one-third of your gross monthly income. This calculator helps you see the payment; lenders also look at your full debt to income ratio.
What is private mortgage insurance (PMI)?
Lenders often require PMI when your down payment is below about 20%. It protects the lender, adds a monthly cost, and usually stops once you owe less than 80% of the home value. Your lender can tell you the exact figure.
Is the interest rate fixed by this calculator?
Yes, it uses a single fixed rate for the whole term. Adjustable-rate loans can change the payment later, which this tool does not model.
This calculator gives an estimate only and is not mortgage advice. Your lender sets the real rate, fees and total payment. Confirm figures with a qualified professional before committing.