Pre-approval (sometimes referred to as conditional approval) will give you a good idea of how much you may be able to borrow from the bank. If a lender pre-approves you for a loan, they will do so for a specific amount, so you can house hunt properties you know you can afford.
It is obligation-free if you're successful, and you can apply more than once.
You can speak with a lender to apply, or you can apply for pre-approval in as little as 20 minutes online!