A $650,000 purchase sits well above Saskatoon's benchmark price of $444,700, so it is already an above-typical Saskatoon home, and mortgages in Canada compound semi-annually rather than monthly, which changes the payment math slightly from what a simple online calculator assumes.
Property tax from the City of Saskatoon, home insurance and, if your down payment is under 20 percent, a mortgage insurance premium plus PST on that premium at closing all add to the number beyond principal and interest, so the true monthly carrying cost is higher than a bare mortgage calculator shows.
A lender can run the real number once you have a rate quote, and that number is what your GDS and TDS ratios actually get tested against. Get your hand-reviewed valuation from Joel Dyck.