Your debt-to-income ratio is one of the first numbers a lender checks before approving a mortgage, car loan or credit line. Enter your total monthly debt payments (rent or mortgage, car loans, minimum credit card payments, student loans and any other required payments) and your gross monthly income before tax, and this calculator divides one by the other to give your DTI as a percentage. It then rates the result the way underwriters do: at or below 36 percent is considered healthy, 37 to 43 percent is a caution zone many lenders still accept, and above 43 percent is high and can make approval harder. Knowing your DTI before you apply helps you see where you stand and how much room you have. It all runs in your browser.