Mortgage Calculator

What this calculator does

It computes the fixed principal-and-interest payment for an amortising mortgage, then builds the full repayment schedule: how much of each payment is interest, how the balance falls, and when the loan ends. Optional ownership costs — property tax, insurance, mortgage insurance, and service charges — are added on top and reported separately, because they are not part of the mortgage itself.

That separation matters. The number a lender quotes is principal and interest; the number that hits your budget every month is the total housing cost. This calculator always shows both and never blurs them into one figure.

What changes the result most

The interest rate and the term dominate. A longer term lowers each payment but raises total interest sharply, because the balance stays high for longer. A larger down payment reduces both the loan and the loan-to-value ratio. Extra payments — recurring or one-time — shorten the schedule and cut interest, with earlier payments saving the most.

Payment frequency matters less than most people expect, with one exception: accelerated biweekly or weekly payments deliberately pay the equivalent of one extra monthly payment per year, which meaningfully shortens the loan.

Formula

For a per-period rate i and n scheduled payments on principal P: payment = P × i × (1 + i)ⁿ ÷ ((1 + i)ⁿ − 1). With a 0% rate, payment = P ÷ n.

The per-period rate depends on the country's convention. Most markets divide the nominal annual rate by the number of payments per year. Canadian fixed mortgages compound semi-annually: i = (1 + rate/2)^(2/periods per year) − 1. The convention in use is shown in the assumptions.

Each period, interest = outstanding balance × i; the rest of the payment (plus any extra payment) reduces the balance, and the final payment is adjusted so the balance lands exactly on zero.

Assumptions

• Payments are made at the end of each period, starting one period after the start date.
• The interest rate is fixed for the whole term.
• The per-period rate follows the selected country's convention (shown above the results); calculations use the reducing-balance method.
• Accelerated biweekly/weekly payments equal half/a quarter of the monthly payment, so the loan pays off early.
• Property tax, insurance and service charges are estimates you enter; they are not part of the mortgage and are shown separately in the total housing cost.
• Upfront costs are paid separately at closing and accrue no interest.
• Values are computed at full precision and rounded only for display.

Content and formulas reviewed on 2026-08-06. See our methodology for how calculations are built and tested.

Worked example

Buying a 500,000 home with 100,000 down leaves a 400,000 mortgage. At 6% over 30 years with monthly payments, i = 0.06 ÷ 12 = 0.005 and n = 360, so the payment = 400,000 × 0.005 × 1.005³⁶⁰ ÷ (1.005³⁶⁰ − 1) ≈ 2,398.20.

Over 360 payments you would pay about 463,353 in interest — more than the amount borrowed. Adding 6,000 per year of property tax and 1,800 of insurance raises the estimated monthly housing cost from 2,398 to about 3,048.

Paying an extra 200 each month would clear the same mortgage roughly 5 years sooner and save roughly 95,000 of interest, based on these inputs.

Frequently asked questions