Is it smarter to pay off student loans aggressively or invest the extra money instead?

Compare the loan's interest rate to what you'd realistically earn investing. If your student loan rate is well above expected long-term market returns, paying it down is a guaranteed, risk-free return and usually wins. If the rate is low, say in the low single digits on older subsidized loans, investing, especially capturing a full 401(k) employer match first, often builds more wealth over time. Most people should do both in a sensible order: grab the match, keep a starter emergency fund, then split extra cash between loans and investments based on the rate. Federal borrowers pursuing forgiveness through PSLF or income-driven plans may deliberately pay the minimum. The Opportunity Cost tool at wealthserene.com/tools/opportunity-cost lets you model paying down debt versus investing side by side.