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Mortgage Repayment Calculator

Estimate monthly repayments, total interest, and amortisation for a home loan.

  • loan
  • home
  • repayment
  • amortisation

About Mortgage Repayment Calculator

A mortgage repayment calculator turns a few numbers — price, deposit, interest rate, and term — into the figures that actually decide whether a house is affordable: the regular payment, the total interest you'll pay over the life of the loan, and how the balance falls month by month.

This calculator uses the standard amortisation formula that banks themselves use, so the monthly figure should match a lender's quote closely. It also models extra payments: even a small recurring overpayment can shave years off a 25- or 30-year mortgage and save a substantial sum in interest, which the schedule and chart make visible at a glance.

How to use

Enter the home price and your deposit; the loan amount is the difference between them. Then set the annual interest rate (as a percentage) and the term in years. The repayment figure updates in real time as you adjust the inputs.

Use the frequency selector to switch between monthly, fortnightly, or weekly schedules — accelerated frequencies pay the loan off faster than monthly does. Add an extra payment per period to see how much interest and time it saves. Currency defaults to Canadian dollars; switch to USD, GBP, EUR, AUD, or NZD as needed. Scroll down for the full amortisation schedule and a balance-over-time chart.

Frequently asked questions

  • How accurate is this against a real bank quote?

    The calculator uses the standard amortisation formula every Western bank uses, with payments computed to the cent using arbitrary-precision arithmetic so the schedule lands on a zero balance. Real-world variation comes from fees, insurance, escrow, and rate-resetting that aren't modelled — but for a fixed-rate loan, the periodic payment figure should be within pennies of a lender quote.

  • Why do fortnightly and weekly payments pay the loan off faster?

    Because there are 26 fortnightly periods or 52 weekly periods in a year, versus 12 monthly periods. With the formula applying the contractual annual rate divided across more, smaller periods, interest compounds slightly less and the equivalent annual cash flow is marginally higher — both nudges shorten the term.

  • What is a sensible "extra payment per period" to test?

    Even an extra 10% of the scheduled payment can shave years off a 25- or 30-year mortgage and cut total interest substantially. Try increments to see the trade-off: the calculator shows the new payoff date and total interest each time, so you can pick a comfortable level of overpayment.

  • Does it model offset accounts or interest-only periods?

    No. The calculator assumes a standard principal-and-interest, fully-amortising fixed-rate loan with regular payments. Offset accounts, redraw, interest-only periods, and variable-rate scenarios aren't modelled here.

  • Which currencies are supported?

    Canadian dollars (the default), US dollars, British pounds, euros, Australian dollars, and New Zealand dollars. Switching the currency only changes the display formatting and symbol — all the underlying math is identical, since amortisation doesn't depend on currency.

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