A pre-approval gives you a solid estimate of the maximum mortgage you qualify for, along with a rate guarantee — typically for 90 to 120 days — that protects you if rates rise while you’re house hunting. It’s based on your income, credit, and down payment information at the time, before a specific property is involved.
A pre-approval isn’t an absolute guarantee of funding — your final approval is still subject to the property itself (appraisal, condition, type) and confirmation that nothing in your financial picture has changed. That said, most realtors won’t take you house hunting seriously without one, and it’s the single best way to shop with confidence and avoid falling in love with a home priced outside your qualifying range.