Lenders use two main measures to determine how much mortgage you qualify for:
Gross Debt Service (GDS) Ratio: This compares your housing costs (mortgage, property taxes, heat, and condo fees if applicable) to your income. Generally, it should not exceed 35% of your gross income.
Total Debt Service (TDS) Ratio: This compares all your debts (housing costs + credit cards, car loans, lines of credit, etc.) to your income. Usually, this must stay below 42–44%.
They also look at your credit score, employment history, down payment, and savings. The goal is to ensure you can manage the payments comfortably.