Should I pay off debt or invest?

The math comes down to comparing your debt’s interest rate against the return you can reasonably expect from investing. The US stock market has historically returned about 10% per year before inflation (roughly 7% after), but that return is volatile and not guaranteed. Paying off a debt, by contrast, "earns" its interest rate with zero risk. Eliminating a credit card balance at 22% APR is a risk-free 22% return — no investment reliably beats that.

A widely used priority order: first, contribute enough to your workplace retirement plan to get the full employer match, because a 50-100% match beats any debt payoff. Second, attack high-interest debt (credit cards, payday loans, most personal loans above ~8%). Third, build a starter emergency fund so surprises do not push you back into debt. Fourth, invest for retirement in tax-advantaged accounts. Low-interest debt like a 3-5% mortgage or subsidized student loan can be paid on schedule while you invest the difference.

For debt in the gray zone (roughly 5-8%), the answer depends on taxes, risk tolerance, and temperament. Tax-deductible interest effectively lowers the rate, tilting toward investing. If market swings would tempt you to sell, or if being debt-free would let you take career risks or sleep better, the guaranteed return of debt payoff has real value that a spreadsheet does not capture.

You do not have to choose all-or-nothing. A split approach — for example, putting 50% of spare cash toward debt and 50% into investments — captures some compounding while steadily shrinking balances, and it is far better than deferring the decision. Run your actual balances and rates through a debt payoff calculator to see how many months and how much interest an extra payment saves, then compare that against projected investment growth.