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Mortgage Calculator

Enter the property price, your deposit, the rate and the term. One setting matters more than people expect: how often interest compounds. Canadian mortgages compound semi-annually by law and most others compound monthly, which changes the payment at the same headline rate.

Leave blank to borrow the full price

Interest compounding

Set this to match your country — it changes the payment

Enter a property price, rate and term to see the monthly payment.

This is principal and interest only

Property tax, buildings insurance, mortgage insurance (PMI, CMHC or equivalent), service charges and arrangement fees are not included, and they vary far too much by country and lender to estimate here. Your actual monthly outgoing will be higher.

How to use this tool

  1. Enter the property price.
  2. Enter your deposit or down payment. Leave it blank to see the figure for borrowing the full price.
  3. Enter the annual interest rate and the term in years.
  4. Set the compounding convention to match your country: semi-annual for Canada, monthly almost everywhere else.
  5. Open the year-by-year breakdown to see how the balance falls over the term.

Formula and method

Monthly payment

M = P × i ÷ (1 − (1 + i)^−n)
P
— amount borrowed, after the deposit
i
— effective monthly interest rate
n
— number of monthly payments

Converting the rate to a monthly figure

i = (1 + r ÷ c)^(c ÷ 12) − 1
r
— annual nominal rate as a decimal
c
— compounding periods per year

With monthly compounding c is 12 and this reduces to the familiar r ÷ 12. With Canada's semi-annual convention c is 2, giving a slightly lower effective monthly rate and therefore a slightly lower payment at the same quoted rate.

Worked examples

$300,000 at 5% over 25 years, compounded monthly

  1. Monthly rate: 0.05 ÷ 12 = 0.00416667
  2. Payments: 25 × 12 = 300
  3. Payment: 300000 × 0.00416667 ÷ (1 − 1.00416667^−300)

About $1,754 a month, with roughly $226,000 of interest over the term.

The same mortgage under the Canadian convention

  1. Semi-annual rate: 0.05 ÷ 2 = 0.025
  2. Effective monthly rate: 1.025^(1÷6) − 1 = 0.004124
  3. The lower periodic rate produces a lower payment

About $1,745 a month — roughly $9 less, and around $2,700 less over the full term.

Notes and limitations

  • The result is principal and interest only. Property tax, buildings and contents insurance, mortgage insurance (PMI in the US, CMHC in Canada), ground rent and service charges are excluded and vary far too much to estimate reliably.
  • Arrangement, valuation and legal fees are not included, and neither are early-repayment charges.
  • The calculation assumes the rate holds for the whole term. Most mortgages are fixed for an initial period and then revert to a variable rate, so treat a 25-year projection as an illustration.
  • The compounding convention is a legal matter in some countries: Canada's Interest Act caps mortgage compounding at semi-annual. Using the wrong setting gives a wrong payment.
  • This is an estimate, not an offer. A lender's affordability assessment considers income, existing debt and stress-tested rates that are not modelled here.

Frequently asked questions

How is a monthly mortgage payment calculated?

The amount borrowed, the effective monthly interest rate and the number of payments are put through the standard amortising loan formula, which finds the fixed payment that clears the debt exactly at the end of the term.

Why do Canadian mortgages produce a different payment?

Canada's Interest Act requires mortgage interest to be compounded no more than twice a year. At the same quoted rate that makes the effective monthly rate slightly lower than r ÷ 12, so the payment is slightly lower. It is a real difference, not a rounding artefact, and it is why a calculator built for one country misleads users of the other.

How much deposit do I need?

It depends on the lender and the country. A larger deposit reduces both the amount borrowed and usually the rate offered, and above certain thresholds it removes the requirement for mortgage insurance. Try different figures above to see the effect on the payment.

Why is the total interest so high?

Because the balance stays large for a long time. On a 25-year mortgage at typical rates the interest often approaches the amount borrowed. Shortening the term raises the monthly payment but cuts the total interest sharply — worth comparing.

Does this include property tax and insurance?

No. Those are genuinely local — rates differ by city, state and province, and insurance depends on the property. Add your own estimates to the figure here to get a realistic monthly outgoing.

Should I use the interest rate or the APRC?

The interest rate gives the contractual payment, which is what this calculator models. The APR or APRC includes fees and is the better number for comparing deals, but it will not match the payment your lender actually charges.

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