GDS and TDS Ratio Calculator
The two ratios a lender checks before approving a mortgage: how much of your gross income goes to housing (GDS) and to all your debts (TDS). Both are measured with the mortgage payment at the stress-test rate.
The rate starts at the average on new uninsured 5-year mortgages in July 2026, from the Bank of Canada (all mortgage rates).
Before tax, everyone on the application
Half of them count
Car loans, credit cards, lines of credit, student loans, support
Within the limits
36.3% / 40.5%
GDS / TDS at the stress-test rate of 6.49%. The limits are 39.0% and 44.0%.
The largest mortgage payment the limits allow on this income is $4,000 a month at the stress-test rate, $319 more than this mortgage. The GDS limit is the one you reach first.
The limits are CMHC's for insured mortgages (less than 20% down). With 20% or more down, lenders set their own, often 35% and 42%. Credit cards and lines of credit usually count at 3% of the balance a month.
What GDS and TDS Measure
The gross debt service ratio is your housing costs as a share of your gross income: the mortgage payment, property tax, heating and half of any condo fees, over what you earn before tax. The total debt service ratio adds every other payment you are obliged to make each month: car loans and leases, credit cards and lines of credit, student loans, support payments. Both are worked out on a monthly basis, and the mortgage payment in them is not the one you will pay but the one at the stress-test rate: your contract rate plus 2 points, or 5.25%, whichever is higher.
Cost | In GDS | In TDS |
|---|---|---|
| Mortgage payment (principal and interest) | Yes, at the stress-test rate | Yes, at the stress-test rate |
| Property tax | Yes | Yes |
| Heating | Yes | Yes |
| Condo or strata fees | Half | Half |
| Car loans and leases | No | Yes |
| Credit cards and lines of credit | No | Yes, 3% of the balance a month |
| Student loans | No | Yes |
| Child or spousal support | No | Yes |
The Limits
CMHC insures a mortgage with a GDS of up to 39% and a TDS of up to 44%, so those are the limits on every insured mortgage, the kind you get with less than 20% down. With 20% or more down, the mortgage is not insured and each lender sets its own limits; the common guideline is 35% and 42%, and a strong credit score or a large down payment can stretch it. Whichever limit you reach first is the one that binds: a buyer with no other debts runs into the GDS limit first, one with a car loan and a credit card balance into the TDS limit.
The ratios are only half of the approval. The lender also checks that the income is steady and documented, that the down payment is yours or a gift, and that your credit history is clean. Our affordability calculator turns the same limits around and shows the price your income supports.
How to Bring the Ratios Down
A longer amortization lowers the mortgage payment, and so both ratios: 30 years instead of 25 is open to first-time buyers and to anyone buying a new build with an insured mortgage, and to any uninsured mortgage. Paying off a car loan or a credit card before applying lowers the TDS directly, and so does paying down a line of credit, since lenders count a share of its balance each month, and for a home equity line often a share of its limit. A co-applicant adds income to the bottom of the ratio. A larger down payment shrinks the mortgage, which helps both ratios and, at 20%, moves you from CMHC's limits to the lender's own.
Today's Mortgage Rates from Lenders
This calculator works with whatever rate you enter. Compare it with the rates lenders are offering right now, fixed and variable, by term. Change the price, down payment or location to match your purchase.
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