The mortgage math, with the lid off

Let's open the hood on the mortgage. Most of us were handed a monthly number without ever seeing the working. No jargon, no scare tactics, just a worked example you can check yourself.

The example. We took the average detached home in three markets: Waterloo Region at $830,071, Toronto's 416 area at $1,562,966, and Ottawa at $725,000. We assumed 20% down, a 25-year mortgage, and 5.14%, the five-year fixed rate a major bank was advertising in mid-October 2026. Payment only: no property tax, heat or insurance.

The payment. On those assumptions the mortgage payment is about $3,915 a month in Waterloo Region, $7,372 in Toronto and $3,420 in Ottawa. The down payment alone is $166,014, $312,593 and $145,000. Put that on a napkin and it gets quiet at the table.

The seatbelt. Lenders do not only ask whether you can pay 5.14%. For uninsured mortgages, the federal banking regulator (OSFI) has them check that you could still pay at the greater of your rate plus 2 points or 5.25%. So at 5.14%, you are tested at 7.14%. It is a seatbelt: a bit annoying until the day it matters.

The income it takes. At the tested rate, and using a common rule of thumb that the payment should be no more than 39% of gross income (our assumption), the household income needed works out to roughly $144,900 in Waterloo Region, $272,800 in Toronto and $126,500 in Ottawa. The median household incomes in the 2021 Census (income year 2020) were $92,000, $97,000 and $102,000. Those incomes are six years old, so the gaps here are probably overstated, but the shape of the picture is the point.

The saving. Say you set aside 10% of gross income, with no investment return and no change in price. One median income takes about 18 years to save the down payment in Waterloo Region, 32 in Toronto and 14 in Ottawa. Two median incomes cut that in half: about 9, 16 and 7 years.

Two incomes, on paper. Two median incomes in Waterloo Region add up to $184,000, above the $144,900 in our example. In Ottawa, $204,000 is well above $126,500. In Toronto, $194,000 still falls short of $272,800. It is a sum, not a promise: whether a lender counts several incomes, and how, is the lender's decision, so talk to a mortgage professional.

Read it with care. We left out property tax, heat, insurance, other debts and closing costs, all of which push the real number up. Prices are from August and September 2026 (Ottawa is a benchmark price from July), and rates and rules change, so treat every figure as an illustration.

Why we are showing you this. The sums are not meant to scare you. They respond to one lever we can all reach: how many people carry the load, and whether the plan is written down before anything is signed. That is what goodDEED works on. We help compatible people who can qualify together find each other and work out the money, the rules and the design of one property. Licensed professionals give the advice, and we coordinate.

Take our short questionnaire at gooddeed.ca/questionnaire, or see how it works at gooddeed.ca/find-a-partner.

Sources: Cornerstone Association of REALTORS (Waterloo Region, August 2026); TRREB Market Watch (September 2026); CREA MLS Home Price Index (Ottawa, July 2026); Statistics Canada 2021 Census (household income, 2020); OSFI, Minimum Qualifying Rate for uninsured mortgages; a major bank's advertised five-year fixed rate (mid-October 2026); goodDEED calculations. This is general information, not legal, tax, mortgage or financial advice.