How loan qualifier calculator works
Lenders cap how much of your monthly income can go toward debt payments using a debt-to-income (DTI) ratio. The back-end DTI includes the new loan payment plus all other monthly debt. Your maximum monthly payment is monthlyIncome times the DTI percentage minus your other monthly debt payments.
This calculator takes your monthly income, other monthly debt payments, a target back-end DTI (commonly 43% for conventional loans, 36% for a stricter standard), the loan's annual interest rate, the term in years, and a down payment. It computes the maximum monthly payment, the maximum loan amount (the present value of that annuity at the given rate and term), and the maximum home price (max loan plus down payment).
If your other debts already eat up the DTI allowance, the tool reports that the loan is not affordable at that ratio — a clear signal to lower the DTI target, pay down debt, or increase income. All math runs in your browser; it is an estimate, not a loan offer.