One of the most common mistakes first-time buyers make is falling in love with a home before knowing what they can actually afford. Lenders look at your debt-to-income ratio (DTI) to decide how large a monthly payment they will approve, and this tool applies the same logic they do. By entering your monthly income, existing debts, available down payment and target interest rate, you get a realistic ceiling on home price rather than a rough guess. This helps you shop within your means, avoid a rejected pre-approval, and understand exactly how paying off a car loan or credit card first could raise the amount a lender is willing to offer you.