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Calculator · Buying
How much can I borrow for a mortgage?
Lenders don't start with the price of the home. They start with your income, your debts and the cost of running the property, then test whether you could still afford the payment at a higher qualifying rate. This calculator walks through the same steps so you can see where your number comes from.
2 min read · Updated 2026-11-10
How lenders work out your maximum
GDS (gross debt service) compares your housing costs — mortgage payment, property tax, heat and half of any condo fee — to your gross monthly income. TDS (total debt service) adds your other monthly debt payments such as car loans, student loans and credit card minimums.
The payment used in these ratios is calculated at the qualifying rate, not the rate you'll actually pay. That's the mortgage stress test, set by OSFI for federally regulated lenders and applied to insured mortgages by the federal government.
A worked example
Example only
- Household income $110,000 · other debts $400/month · property tax $300/month · heat $120/month
- Contract rate 4.50% → qualifying rate 6.50%, 25-year amortization
- Use the calculator above to see how a condo fee or a car payment changes the answer.
What changes the number
- Paying down or closing out monthly debts often helps more than a raise.
- A longer amortization (where eligible) lowers the qualifying payment.
- Condo fees and higher property taxes reduce room under GDS.
- Down payment affects price and insurance, not the debt-service ratios themselves.
Frequently asked questions
What is the mortgage stress test rate?
For federally regulated lenders, you must qualify at the greater of your contract rate plus 2 percentage points or 5.25%. The payment at that rate is used in your GDS and TDS ratios.
What are GDS and TDS limits?
For insured mortgages, CMHC's maximums are 39% GDS and 44% TDS. Conventional lenders set their own limits, which are often similar. Some lenders adjust limits based on credit score.
Do condo fees count when qualifying?
Usually yes. Lenders commonly include 50% of the monthly condo fee in housing costs, which lowers the maximum mortgage compared with a freehold home with the same price.
Is this a pre-approval?
No. It's an illustration. A pre-approval needs a credit check and documents, and is still subject to the lender approving the property.
Does my down payment change how much I can borrow?
Your income and debts set the maximum mortgage. Your down payment then sets the maximum price and whether mortgage default insurance is needed.
Sources
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