Debt vs Investing Calculator
Compare whether extra monthly cash might have a stronger impact paying down debt or being invested. This page targets a high-intent question competitors often answer only with text.
What the calculator cannot decide
- Risk. Paying debt has a known return equal to the avoided interest. Investing has uncertainty.
- Emergency cash. Do not ignore liquidity just because a spreadsheet says one option wins.
- Taxes and fees. Investment taxes, platform fees and loan penalties can change the result.
Related comparison pages
FAQ
Is paying off debt a guaranteed return?
Avoided interest is usually more certain than investment return, especially with high-interest debt.
When might investing still make sense?
Employer matches, tax advantages and very low-interest debt can change the decision.
Does this replace financial advice?
No. Use it as a comparison tool, not a personal recommendation.
The comparison, stated honestly
Paying down debt returns exactly the interest rate you stop paying, guaranteed and tax-free. Investing returns an uncertain amount that may be higher. That asymmetry — certain versus expected — is the whole decision, and it is usually presented as a rate comparison when it is really a risk comparison.
| Debt interest rate | Guaranteed return from repaying | Investing at 7% is expected to | Reasonable default |
|---|---|---|---|
| 18% (credit card) | 18% | lose to it heavily | Repay first |
| 9% (personal loan) | 9% | lose to it on average | Repay first |
| 6% (older mortgage) | 6% | roughly match it | Either — depends on you |
| 3% (low fixed mortgage) | 3% | beat it on average | Invest, if you can hold your nerve |
| 0% (promotional) | 0% | beat it easily | Invest, but never miss the deadline |
The investing column is an expectation, not a promise. The repayment column is neither.
To see the size of the effect: $10,000 of credit card debt at 18% costs about $14,432 in interest over five years if left to compound. The same $10,000 invested at 7% earns roughly $4,176 over the same period. Nothing about market returns closes that gap.
Employer matching on a retirement account beats almost any debt, because it is an immediate return before any market growth. An emergency fund also comes first — without one, the next unexpected expense goes back onto the card and undoes the repayment. And a debt that causes you to lose sleep has a cost that does not appear in any of these columns.
A workable order of operations
- 1. Minimum payments on everything. Missed payments cost more than any optimisation gains.
- 2. Any employer match. A 50% match is a 50% return before the market does anything.
- 3. A small emergency buffer. One month of expenses is enough to stop a setback becoming new debt.
- 4. High-interest debt, above roughly 8%. The guaranteed return is hard to argue with.
- 5. A fuller emergency fund. Three to six months, depending on how stable your income is.
- 6. Invest, and treat low-rate debt as a fixed cost. Below about 5%, most people are better off investing the difference — provided they actually invest it.
The thresholds are conventions rather than laws, and the middle band from roughly 5% to 8% is genuinely ambiguous. In that range the tie-breaker is usually temperament: the person who will sleep better debt-free should clear the debt, because a plan you abandon returns nothing at all.
Questions about debt versus investing
Should I pay off debt or invest?
Compare the debt's interest rate to your expected investment return, then weight the debt side because its return is guaranteed. Above roughly 8%, repaying usually wins; below roughly 5%, investing usually does.
Does paying off debt count as a return?
Yes, and a very good one. Eliminating an 18% debt is equivalent to earning 18% risk-free and tax-free — a return no ordinary investment offers reliably.
What about a mortgage?
Mortgage rates are usually low enough that investing has the higher expected outcome, but overpaying is guaranteed and reduces the risk of the loan itself. Many people sensibly do both.
Should I invest while I have credit card debt?
Only up to any employer match, which is a larger immediate return than the card charges. Beyond that, clearing high-interest debt is very hard to beat.