Mortgage Calculator
Estimate your monthly mortgage payment, total interest, and payoff cost from the home price, deposit, rate, and term.
Content updated July 1, 2026
Principal & interest only. Property tax, insurance and any mortgage insurance are additional.
A mortgage is almost certainly the biggest loan you'll ever take out, and even a small change in the interest rate or term can shift the total cost by tens of thousands. This mortgage calculator shows you the monthly payment on a repayment (principal-and-interest) mortgage, plus the total interest you'll pay over the life of the loan.
Enter the property price, your deposit or down payment, the annual interest rate, and the term in years. The result updates instantly so you can compare scenarios — a larger deposit, a shorter term, or a slightly lower rate — and see exactly what each one does to your monthly budget and lifetime cost.
The Mortgage formula
M = P · r · (1 + r)ⁿ / ((1 + r)ⁿ − 1)M = monthly payment · P = amount borrowed (price − deposit) · r = monthly interest rate (annual rate ÷ 12, as a decimal) · n = total number of payments (years × 12).
Worked example
Borrow $300,000 at 6% over 30 years. Here P = 300,000, r = 0.06/12 = 0.005, and n = 360. That gives M = 300,000 × 0.005 × (1.005)³⁶⁰ / ((1.005)³⁶⁰ − 1) ≈ $1,799 a month, and about $347,500 in total interest over the full term.
How your mortgage payment is calculated
Your monthly payment is worked out using the standard amortization formula that lenders use worldwide: M = P · r · (1 + r)ⁿ / ((1 + r)ⁿ − 1), where P is the amount borrowed, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12).
Early in the loan, most of each payment goes toward interest and only a little toward the balance. As the balance falls, more of every payment chips away at what you owe. That's why paying a little extra in the early years — or choosing a shorter term — saves so much interest overall.
What this calculator does and doesn't include
The figure shown is the principal-and-interest payment on the mortgage itself. Your real monthly housing cost may also include property taxes, homeowners or buildings insurance, and — if your deposit is under 20% — private mortgage insurance (PMI) or a lender's mortgage insurance premium. Budget for these on top of the number here.
The calculator assumes a fixed interest rate for the whole term. If you're on a variable or adjustable rate, treat the result as today's snapshot and re-run it whenever your rate changes.
Ways to reduce what you pay
Increase your deposit: borrowing less directly cuts both the monthly payment and total interest, and a bigger deposit often unlocks a lower rate.
Shorten the term: a 20-year mortgage costs more per month than a 30-year one but far less in total interest. Try both and compare.
Overpay when you can: even one extra payment a year meaningfully shortens the loan. Check your lender allows penalty-free overpayments first.
Frequently asked questions
▶How much deposit do I need for a mortgage?
Many lenders accept 5–10% of the property price, but 20% or more usually means a better interest rate and avoids mortgage insurance. Use the calculator to see how different deposits change your monthly payment.
▶Does this include property tax and insurance?
No — it shows the principal-and-interest payment on the loan only. Add your local property tax, home insurance, and any mortgage insurance separately to get your full monthly housing cost.
▶Is a shorter mortgage term cheaper?
Yes, in total. A shorter term has higher monthly payments but you pay far less interest overall because you're borrowing the money for fewer years.
▶How is a mortgage payment calculated?
Lenders use the amortization formula M = P · r · (1 + r)ⁿ / ((1 + r)ⁿ − 1), where P is the amount borrowed, r is the monthly interest rate, and n is the total number of monthly payments. It spreads the loan so every payment is equal.
▶What is PMI and when do I pay it?
Private mortgage insurance (PMI), or a lender's mortgage insurance in some countries, is a monthly charge lenders add when your deposit is under 20%. It protects the lender, not you, and usually falls away once you've built up enough equity.
▶What's the difference between APR and the interest rate?
The interest rate is the pure cost of borrowing. The APR also includes certain fees and charges, so it's a fairer figure for comparing mortgage deals from different lenders.
▶Can I pay off my mortgage early?
Often yes, and overpaying goes straight to the principal, cutting both the term and total interest. Check first whether your deal has early-repayment charges or an annual overpayment limit.
Learn more
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Open calculator →Disclaimer: Mortgage Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.