How a Canadian mortgage payment is calculated

The formula uses the standard amortizing-loan equation with rates compounded semi-annually, not in advance — the Canadian Bank Act convention. The equivalent per-period rate is derived so the math is consistent whether you choose monthly, semi-monthly, bi-weekly, or weekly payments. This semi-annual compounding produces slightly lower payments than the US convention (which compounds monthly), so American mortgage calculators give the wrong answer for a Canadian mortgage.

Payment frequencies — what actually changes

Monthly: 12 payments/year, simplest, lender default
Semi-monthly (twice a month): 24 payments at half the monthly amount; same annual outflow, slightly less interest
Bi-weekly (every 2 weeks): 26 payments at half the monthly; same annual outflow
Accelerated bi-weekly: 26 payments at half the monthly = 13 monthly equivalents per year (one extra payment); pays off ~3 years sooner
Weekly: 52 payments at quarter of monthly; same annual outflow
Accelerated weekly: 52 payments at quarter of monthly = 13 monthly equivalents per year; same effect as accelerated bi-weekly

The wealth-building options are the accelerated versions — both pay the equivalent of one extra monthly payment per year, going entirely to principal and compounding over the remaining amortization. See the bi-weekly vs monthly calc for the savings math.

What drives your payment most

Three numbers — and one matters more than people think:

Mortgage amount: linear effect. Each $100k of mortgage adds ~$570/month at 4.84% / 25 years.
Interest rate: the largest swing factor. Same $720k mortgage at 25-year amort: 3.99% = $3,781/mo; 4.84% = $4,118/mo; 5.99% = $4,602/mo. A 1% rate change moves your payment about 9%.
Amortization: longer = lower payment but more total interest. Same $720k at 4.84%: 25 years = $4,118/mo, $515k total interest; 30 years = $3,768/mo, $635k total interest. The extra 5 years saves $350/mo but costs $120k extra interest.

Fixed vs variable rate — which to plug in

Use your contracted rate. For a 5-year fixed mortgage, plug in the 5-year fixed rate; for a variable, the current variable rate. The payment shown is what you pay during the current term — at renewal (typically 5 years later) you'll re-amortize at whatever rates are then available. See the fixed vs variable calc for a deeper comparison.

Insured vs uninsured — does it change the math?

If your down payment is under 20%, your mortgage is insured (CMHC, Sagen, or Canada Guaranty). The insurance premium is added to your mortgage balance and financed over the amortization — increasing both your monthly payment and total interest. See the default insurance calc for current premium tiers and the down payment + CMHC calc for the stack-up.

What this calculator does not include

Property tax — pull your city's rate via the property tax calc
Heating + condo fees — relevant for affordability ratios, not the mortgage payment itself
HELOCs — separate product with its own rate and minimum payment structure
Provincial land transfer tax — one-time closing cost, see the LTT calc
CMHC premium when insured — added to the mortgage balance via the default insurance calc

Worked example — typical Canadian first-time buyer

$720,000 home, $80,000 down (11.1% down → insured), 4.84% 5-year fixed, 25-year amortization, monthly payments:

Mortgage before insurance: $640,000
CMHC premium (~3.10% at 88.9% LTV): $19,840 — added to balance
Total mortgage financed: $659,840
Monthly payment: ~$3,775
Total interest over 25 years: ~$472,000
Total paid over 25 years: ~$1,132,000

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