Aggregate unsecured debt (credit card, medical, student loans, tax, all creditors who do not have liens) divided by annual gross income.

Unsecured debt/annual gross income=debt percentage  

0-10%            A modest debt burden.  

0-20%          Red flags, but still resolvable.                       

20-35%          Alarm bells.  You need unbiased professional help.  

Over 35%       Little hope of avoiding bankruptcy.  

Read more about Debt-to-Income Ratio