Is it better to pay off debt or invest extra cash?

Compare the numbers. Paying off debt is a guaranteed, risk-free return equal to its interest rate, so high-rate debt almost always wins: clearing a 24% credit card beats any realistic investment return, and it's tax-free. For that reason, knock out high-interest debt before investing beyond any employer 401(k) match. The match is the exception – it's typically a 50–100% instant return, so capture it even while paying down debt. The calculus flips for low-rate debt: a 3–4% mortgage or subsidized student loan often costs less than the long-run return you might earn investing, so many people invest while paying those on schedule. Factor in your risk tolerance and the peace of mind that being debt-free brings, which has real value beyond the math. As a rule: match first, then high-rate debt, then invest, then low-rate debt. Run the comparison at wealthserene.com/tools/opportunity-cost.