How do I decide how much student debt is reasonable to take on for my major?

A widely used guideline is to keep total student loan debt at or below your expected first-year salary after graduation, so the payments stay manageable on a standard 10-year plan. That ratio matters more than the raw number: $40,000 of debt is very different for an engineer earning $75,000 than for a graduate entering a $35,000 field. Research realistic starting salaries for your major and target career using the Bureau of Labor Statistics Occupational Outlook Handbook, then compare that to the debt you'd carry. If projected payments would exceed roughly 8 to 10 percent of your expected gross income, consider cheaper schools, more aid, community college for prerequisites, or a different funding mix. Borrowing decisions made at 18 shape your budget for a decade or more.