Applying for a mortgage is an excruciating process. What documents does the bank need? Will you be approved? Or will you be denied and pushed out the door with your tail between your legs?

For most Americans, one of the biggest issues concerns pre-existing debt. Thanks to credit cards, student loans, and car payments, many people's current debt loads are already high, leaving little room for a mortgage -- to say nothing of property taxes and insurance.

The good news is that it's easy to know where you stand in this regard. As Motley Fool contributor John Maxfield discusses in the following video, there's one statistic in particular that banks use to gauge this. Known as the debt-to-income ratio, it measures the proportion of your gross income that goes toward paying your debts on a monthly basis -- with the estimated mortgage payment included.

Is your DTI too high? Watch the video to find out.