Average student loan debt is ~$30K. http://blogs.wsj.com/economics/2015/05/08/congratulations-class-of-2015-youre-the-most-indebted-ever-for-now/ What kind of starting salary do you think you’ll have if $60K=20%? One rule of thumb is no more than one year starting salary (which in many cases ~$40K, more for engineers). Most people on the boards recommend no more than the Stafford limit (<$30K).