Debt-to-income RatiosThe debt-to-income ratio is the way mortgage lenders decide how much money you can afford to borrow. It is the percentage of your monthly gross income used to pay your monthly debts (not monthly living expenses). Two calculations are involved, a front ratio and a back ratio, written in ratio form, i.e., 33/38. The first number indicates the percentage of your monthly gross income used to pay housing costs, such as principal, interest, taxes, insurance, mortgage insurance…