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Mortgage Affordability Calculator Canada — GDS/TDS & DTI

Find out how much home you can afford in Canada or the US. Enter income, debts, and down payment — we calculate your maximum purchase price using GDS/TDS ratios (Canada) or DTI (US) and show whether you qualify. Free.

Canadian mortgage qualification uses two ratios: GDS (Gross Debt Service, housing costs ÷ income) must be ≤ 39%, and TDS (Total Debt Service, all debts ÷ income) must be ≤ 44% for insured mortgages under OSFI B-20. Enter your gross income, debts, and local property tax estimate to find your maximum home price and see exactly where you stand on both ratios.

Select your region for jurisdiction-specific rules (deposit caps, rent increase limits, transfer taxes, and more).

Inputs

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Results

Maximum Purchase Price

$544,173

Maximum Mortgage

$444,173

GDS / Front-End DTI

32.00%

TDS / Back-End DTI

37.00%

Qualifies

✓ Qualifies

Understanding This Calculator

Learn how lenders turn your income and debts into a maximum purchase price using GDS/TDS ratios in Canada or DTI ratios in the US.

How the math works

Lenders cap the share of gross income that can go to housing. In Canada: GDS = (mortgage payment + property tax + heating) ÷ gross income, and TDS = GDS costs + all other debt payments ÷ gross income. Insured mortgages typically allow GDS up to about 39% and TDS up to 44%; many lenders prefer 32% GDS. US lenders use the equivalent front-end (~28%) and back-end (~43%) DTI ratios.

The calculator works backwards: it finds the largest monthly payment that keeps both ratios under their limits, converts that payment into a mortgage amount at your rate and amortization, then adds your down payment to get the maximum purchase price.

Worked example

Using the defaults: $120,000 income ($10,000/month), 5% rate, 25-year amortization, $100,000 down, $5,000 property tax, $2,400 heating/insurance, and $500 other monthly debts.

  1. Housing budget at a 39% GDS cap: $3,900/month
  2. Less tax ($417) and heating ($200): about $3,283 available for the mortgage payment
  3. TDS check: 3,900 + 500 = $4,400 = 44% of income — right at the limit
  4. A $3,283 payment at 5% over 25 years supports a mortgage of roughly $565,000, so a purchase price near $665,000 with the down payment

Your qualifying number will be lower at the stress-test rate (contract + 2%).

How to read the result

The maximum purchase price is a ceiling, not a target. Check where your GDS and TDS land:

  • GDS under ~32% and TDS under ~40% — comfortable, with room for rate renewals and surprises.
  • Ratios at the 39%/44% limits — you qualify on paper but have little slack; a rate rise at renewal or a job change bites immediately.
  • Over the limits — reduce debts, add down payment, or lower the price.

Remember the calculator does not include CMHC premiums, closing costs, or the federal stress test in your budget. Confirm actual qualification with a lender or licensed broker before making offers.

Frequently Asked Questions