Canadian Mortgage Calculator — Real Numbers, Canadian Rules

The stress test: the rate you qualify at is not the rate you pay

Every federally regulated lender in Canada must run a second, higher-rate calculation before approving you — the minimum qualifying rate, commonly called the stress test. For an uninsured mortgage, OSFI sets that rate as the greater of your contract rate plus 2 percentage points, or a floor of 5.25%. OSFI's Guideline B-20 states this qualifying rate applies to all uninsured mortgages, and that high-ratio mortgages — anything above 80% loan-to-value — must be insured in the first place.

This calculator's monthly-payment result always uses your actual contract rate. The stress test is a separate, higher hurdle lenders use to size your maximum approved loan against your income (your GDS and TDS ratios), not a rate that changes your real payment. Two contract rates land on opposite sides of the floor differently: a 4.79% contract rate stress-tests at 6.79% (4.79% + 2, which beats the 5.25% floor), while a 2.99% contract rate stress-tests at the 5.25% floor itself, since 2.99% + 2 = 4.99% is below it.

Semi-annual compounding: the formula behind the number

The reason this calculator's payment differs from a US mortgage calculator fed the same rate is the Interest Act, s. 6: a mortgage with a blended principal-and-interest payment cannot charge interest unless the contract states the rate "calculated yearly or half-yearly, not in advance." Canadian lenders use the half-yearly option on fixed-rate mortgages, so your nominal annual rate is converted to an effective monthly rate with the formula r = (1 + j/2)^(1/6) − 1, where j is your quoted annual rate. A US-style monthly-compounding calculator instead uses r = j/12, a different and larger effective monthly rate.

On a 4.79% contract rate, the semi-annual formula gives a monthly rate of 0.3952%; j/12 would give 0.3992%. The gap looks small per month, but it compounds over a 25- or 30-year amortization, so a calculator built for US mortgages will consistently overstate a Canadian borrower's interest cost and understate how much of each payment goes to principal.

CMHC premium tiers, and the price cap on insurability

Below 20% down, CMHC insurance is mandatory, and CMHC's own premium table prices it by loan-to-value, not by a flat rate: up to 65% LTV costs 0.60% of the loan, rising in five bands to 4.00% for a 90.01–95% LTV mortgage (95% LTV — a 5% down payment — is the minimum allowed). The premium is calculated on the loan amount and normally added to the mortgage principal, which is why it raises your total interest cost even though you never write CMHC a separate cheque.

CMHC insurance is not available on every home. CMHC's eligibility page states the purchase price must be below C$1,500,000 for a homeowner loan — a strict ceiling, not a rounded figure — and sets the minimum down payment at 5% on the first C$500,000 of price plus 10% on any portion between C$500,000 and the price cap. The same page sets the qualifying limits lenders check your income against: gross debt service (GDS) at or under 39% of gross household income, and total debt service (TDS) at or under 44%.

The premium itself can be rolled into the mortgage, but the tax on it cannot. CMHC's own page notes that Ontario, Quebec and Saskatchewan charge provincial sales tax on the CMHC premium, and that tax "cannot be added to the loan amount" — it is cash due at closing, on top of your down payment. On the C$18,135 premium above, an Ontario buyer owes 8% PST as a separate closing cost: C$1,450.80, due at closing rather than amortized over 25 years.

Term vs. amortization: what this calculator assumes stays fixed

This calculator holds your rate constant for the full amortization you select, but that is not how a Canadian mortgage actually works. FCAC's own definition separates term — the length of your rate contract, typically up to five years — from amortization, the full schedule to a zero balance. Your rate resets at every renewal, so the semi-annual-compounding payment above is only accurate for your current term; plug in your renewal rate on the mortgage renewal calculator once you're within a few months of your term ending, rather than assuming today's rate holds for the full amortization.

Funding the down payment: FHSA and HBP are not either/or

Before you reach the compounding math, first-time buyers can assemble the down payment from two registered accounts, and the rules let you use both on the same home. The First Home Savings Account gives you C$8,000 of contribution room in your first year toward a C$40,000 lifetime maximum, and CRA confirms an HBP withdrawal and an FHSA qualifying withdrawal can both apply to the same qualifying home, as long as each withdrawal meets its own conditions at the time you make it — the current HBP withdrawal limit is C$60,000 per person, RRSP funds you repay over 15 years rather than a tax-free withdrawal like the FHSA. Run the two together on the FHSA calculator and the RRSP Home Buyers' Plan calculator before you land on the down payment figure you type into the calculator above — a bigger down payment changes both your LTV tier and whether CMHC insurance applies at all.