Pay Off Debt or Invest Calculator

The core rule is to compare your debt's effective interest rate against your expected after-tax investment return. If your debt rate is higher, paying it off first gives you a guaranteed return equal to that rate. If your investment return exceeds your effective debt cost, investing may generate more wealth over time. This calculator does that comparison automatically using your specific numbers.

The effective rate is the true cost of your debt after accounting for any tax deductibility. For example, if your mortgage rate is 7% and your tax rate is 22%, your effective cost is roughly 5.46% because the interest reduces your taxable income. Comparing this adjusted rate to your investment return gives you a more accurate decision.

Generally, no. Credit card rates often exceed 20% APR, which is very difficult to beat consistently with investments. Paying off high-interest debt first is almost always the mathematically superior choice. Once the high-rate debt is cleared, redirecting that payment toward investments can accelerate wealth-building significantly.

Yes. The calculator uses your marginal tax rate to compute an after-tax investment return, which is then compared to the effective cost of your debt. This provides a more realistic picture than comparing raw rates, especially for taxable investment accounts.

For best results, focus on your highest-interest debt first (the avalanche method) and run the calculator using that debt's rate. Once that debt is paid off, re-run the calculator with the next debt to see whether continuing to pay down debt or shifting to investing makes more sense at that stage.

Yes, in some situations. If your employer offers a 401(k) match, contributing enough to capture that match is almost always worthwhile — it's an immediate 50–100% return. Similarly, if your debt carries a very low rate (e.g. a 3% auto loan) and you expect higher investment returns, investing simultaneously can be rational. The calculator helps you quantify both scenarios.

A commonly used benchmark for a diversified stock index fund is 7% annually (a conservative estimate of the long-run historical average after inflation). For a balanced portfolio, 5–6% is a reasonable assumption. Avoid using very high rates like 15%+ unless you have specific reason to expect them — optimistic inputs can lead to misleading conclusions.

Absolutely. Enter your remaining mortgage balance as the debt, your mortgage rate as the interest rate, and mark interest as tax-deductible if you itemize deductions. The calculator will compute the effective mortgage cost and compare it to your expected investment return over your chosen time horizon.