The number above is principal and interest only. Your actual monthly cost will be higher, often by a few hundred dollars, and it's worth knowing what's missing before you build a budget around it.
Property tax. Billed by the city. Whether you pay it directly or your lender collects it alongside your mortgage payment, it's a real monthly cost.
Condo fees, if the place has them. Plenty of townhouses do, not just apartment-style units. They vary widely between buildings and they can go up, so two places at identical prices can carry very different monthly costs.
Mortgage default insurance, if your down payment is under 20%. It protects the lender, not you. It's normally added to the mortgage rather than paid up front, so you borrow more than this calculator assumes and your real payment is higher than what it shows.
Home insurance, which your lender will require before closing.
Run your number here, then add those costs on top before you settle on a budget. When you're getting close to making an offer, a mortgage broker can give you a real figure with all of it included, and that conversation costs you nothing.