Mortgage Calculator
The Mortgage Calculator estimates the monthly repayment on a home loan and the total interest over its life. Enter the loan amount, the annual interest rate and the term in years to see your monthly payment, the total repaid and how much of that is interest.
What drives a mortgage payment
A mortgage is a long-term loan secured against a property, repaid in equal monthly instalments. Three numbers decide the payment: how much you borrow, the interest rate, and how many years you take to repay. Because the term is usually long, even small rate changes move the total interest by a large amount.
The formula
The monthly payment uses the same reducing-balance formula as any loan: M = P × r × (1 + r)n / ((1 + r)n − 1), where P is the loan amount, r is the monthly rate (annual ÷ 12 ÷ 100) and n is the number of monthly payments (years × 12).
A worked example
Borrow 3,00,000 at 6% for 30 years. The monthly rate is 0.005 and n = 360, giving a payment of about 1,799 a month. Over 30 years that is roughly 6,47,500 repaid, so about 3,47,500 is interest, more than the amount borrowed. Cut the term to 20 years and the monthly payment rises to about 2,149, but total interest falls dramatically because you hold the debt for a decade less.
Beyond the core payment
Your real monthly housing cost often includes property tax, home insurance and, on smaller deposits, mortgage insurance. This calculator focuses on principal and interest, which is the largest and most comparable part. Overpaying even a little each month, where your lender allows it, can shorten the term and save substantial interest.
How to use
- Enter your details in the fields above. The Mortgage Calculator accepts everyday values and checks them as you type.
- Press the action button (or just start typing for live tools) to run the calculation.
- Read your result, along with any supporting figures, in the clearly labelled result box.
- Use Copy result to grab the answer, Reset to start again, or Copy link to share this tool.
Why use this tool
Finance Wave built the Mortgage Calculator to be genuinely useful: it validates your input so you never see a broken result, formats numbers for your region automatically, and stays readable in both light and dark mode. Because everything happens on your device, it is private by design and keeps working even without an internet connection once the page has loaded.