Mortgage · Canada
GDS and TDS worked examples.
See exactly how a Canadian lender gets from income to a maximum mortgage. The calculator shows each step: the 39% and 44% limits, what housing costs and debts use up, and which ratio binds.
Short version. GDS (gross debt service) is housing costs over gross income and CMHC restricts it to 39%. TDS (total debt service) is housing costs plus all other debts over gross income, restricted to 44%. You qualify for the smaller of the two mortgages. On $100,000 with $500 of debts the TDS binds and the maximum mortgage is about $380,600.
The rules behind every figure on this page: the qualifying rate is the greater of your contract rate plus 2% or 5.25% (OSFI, page modified 29 January 2026); CMHC restricts GDS to 39% and TDS to 44%; and the minimum down payment is 5% of the first $500,000, 10% of the portion up to $1.5 million and 20% at $1.5 million or more (FCAC). Checked retrieved 15 October 2026.
Inputs
Result
Fill the form and press Calculate.
Worked numbers
Both examples come from the same engine as the calculator above; change the inputs to reproduce them. Figures are rounded to the cent or to the nearest $100.
Example 1: $100,000 income, $500 of monthly debts
Assumptions: $500 of other monthly debts, a 5% contract rate (tested at 7%), 25-year amortization, property tax at 1% of the price a year and $100 a month for heating. Those are assumptions you can change in the form, not published figures.
| Gross monthly income | $8,333.33 |
|---|---|
| GDS limit (39%) | $3,250.00 |
| TDS limit (44%) | $3,666.67 |
| Heat plus 50% of condo fees | $100.00 |
| Other monthly debts | $500.00 |
| Room for mortgage + property tax, GDS | $3,150.00 |
| Room for mortgage + property tax, TDS | $3,066.67 |
| Binding limit | TDS |
| Maximum mortgage / price | $380,600 / $480,600 |
| Resulting GDS / TDS | 38.0% / 44.0% |
Example 2: $100,000 income, no debts, $400 monthly condo fees
Same assumptions, but no other debts and $400 a month of condo fees, of which CMHC counts 50%.
| Gross monthly income | $8,333.33 |
|---|---|
| GDS limit (39%) | $3,250.00 |
| TDS limit (44%) | $3,666.67 |
| Heat plus 50% of condo fees | $300.00 |
| Other monthly debts | $0.00 |
| Room for mortgage + property tax, GDS | $2,950.00 |
| Room for mortgage + property tax, TDS | $3,366.67 |
| Binding limit | GDS |
| Maximum mortgage / price | $365,800 / $465,800 |
| Resulting GDS / TDS | 39.0% / 39.0% |
The formulas
GDS = (mortgage principal and interest + property tax + heat + 50% of condo fees) ÷ gross monthly income, at most 39%. TDS = (the same housing costs + all other debt payments) ÷ gross monthly income, at most 44%. CMHC requires property tax and heat in both, and for unsecured lines of credit and credit cards it counts a payment of no less than 3% of the outstanding balance (CMHC).
Mortgage payments are measured at the qualifying rate, the greater of the contract rate plus 2% or 5.25% (OSFI, CMHC), and CMHC's definition includes the insurance premium in the loan amount, which this tool does not model. The maximum mortgage is the largest loan for which the smaller room under GDS and TDS still covers the payment plus property tax.
How this calculator works
It finds the largest mortgage whose payment at the qualifying rate keeps both ratios inside the limits, then adds your down payment. GDS is mortgage payment + property tax + heating + 50% of condo fees, at most 39% of gross monthly income. TDS adds every other monthly debt payment and is capped at 44%. Payments use Canadian semi-annual compounding. The same engine as the main mortgage affordability calculator is used, so the two always agree for the same inputs.
Not included: the CMHC insurance premium (added to the loan when the down payment is under 20%, so treat results with less than 20% down as an upper bound), your credit score, rental income, and any tighter lender-specific limits. A pre-approval from a lender or broker is the only figure that counts.
Sources (retrieved 15 October 2026)
Frequently asked questions
What is the difference between GDS and TDS?
GDS counts housing costs only: mortgage payment, property tax, heat and half of any condo fees. TDS adds every other monthly debt payment. CMHC restricts GDS to 39% and TDS to 44%.
Which ratio is the one that limits me?
Whichever leaves less room. In example 1 it is TDS because of $500 of other debts; in example 2 it is GDS because there are no other debts. The calculator names the binding ratio for your numbers.
Are 39% and 44% always the limits?
They are CMHC's maximums for insured mortgages. Lenders can apply their own limits, which may be tighter, so treat them as the usual ceiling rather than a promise.
Why does the qualifying rate matter?
Payments in both ratios are calculated at the greater of your contract rate plus 2% or 5.25%, not the rate you will actually pay, which is the mortgage stress test.
More ways to ask the same question
How Much House Can I Afford in Ontario · How Much House Can I Afford in BC · How Much House Can I Afford in Alberta · How Much House Can I Afford in Quebec · Mortgage on a $80,000 Salary · Mortgage on a $100,000 Salary · Mortgage on a $150,000 Salary · How Much House Can I Afford: Single vs Couple
Estimate only — not lending advice
This is an educational estimate. It runs in your browser and nothing you enter is sent anywhere. Approval depends on credit, employment, the actual property tax and heating cost, and lender policy; confirm with a lender or mortgage broker.