If you're thinking about buying a home this year, no doubt the thought has crossed your mind about whether you make enough money to qualify for a mortgage -- or, at least, for a mortgage of sufficient size to buy a suitable house. 

Fortunately, the answer to this question is relatively straightforward. As Motley Fool contributor John Maxfield explains in the following video, mortgage lenders approach this question in a systematic manner. So systematic, in fact, that most people can figure out the answer in a matter of minutes.

The key to the problem is the debt-to-income ratio, which compares how much you make to how much you are already paying out each month to service your preexisting debts such as credit cards, student loans, and car payments. As John discusses in the video, the key is to keep this figure below 45% -- that is, after the potential mortgage payments are factored in as well.