In my search for a home mortgage I have found this Microsoft Excel worksheet to give me a rough idea of what I would be able to qualify for and how different variables account for what I am able to qualify for. I called around to different mortgage companies and found out what thier Housing Cost Ratio and the Total Debt Service Ratios are. I found that Wells Fargo goes up to 34 for the Housing and 48 for the Total Debt Ratios. Using this worksheet you can see if it is your income or your monthly debt payments that are limiting your purchase power.
http://office.microsoft.com/en-us/templates/TC010267421033.aspx?pid=CT101444811033
