Pay Off Debt or Invest Calculator
Send the same spare dollars down both paths over one horizon, scored on the same measure — investments after tax, minus any debt left. The number worth reading is the break-even: the assumed return at which the two land level.
The debt and the money in question
This one is contractual: clearing the balance avoids exactly this rate, with no uncertainty.
Paid on both paths. Only the extra below is actually in question.
The contested money: thrown at the debt, or invested instead.
Your assumption, not a forecast. Nothing here guarantees it, and real returns arrive unevenly.
Measured as investments after tax minus any debt still outstanding, on the same date, with identical monthly outlay.
- Break-even return
- 19.75%
- Debt gone (debt first)
- Year 1, month 7
- Debt gone (invest first)
- Year 5, month 4
Investing only comes out ahead above an assumed 19.75% a year on these inputs. That threshold sits above the debt's 19% APR partly because gains are taxed at 15% while interest avoided is not.
| Path | Interest paid | Invested (after tax) | Debt left | Net worth |
|---|---|---|---|---|
| Debt first, then invest | $1,299.15 | $66,154.54 | $0.00 | $66,154.54 |
| Invest while paying the minimum | $4,773.54 | $62,472.45 | $0.00 | $62,472.45 |
How both paths are made genuinely comparable
Each month, both paths spend the required payment plus the extra — the same total, every month, for the whole horizon. The debt-first path sends all of it to the balance until the debt is gone, then invests all of it. The invest-first path sends only the required payment to the balance and invests the rest, then invests everything once the debt clears. Interest accrues at one twelfth of the APR; investments grow at one twelfth of the assumed annual return, with contributions made at the end of each month.
Net worth = (Invested − Tax on gains) − Debt remaining, at the same month on both paths- Tax on gains
- Gains × tax rate, applied once at the horizon; a loss is not credited
- Debt remaining
- Subtracted, so an unpaid balance is never free
- Break-even
- The assumed return where the two net worths are equal
The break-even return is found by bisection rather than asserted. The gap between the paths narrows steadily as the assumed return rises — the invest-first path holds more, earlier, so it gains more from a higher rate — which means a sign change inside the supported range is a single crossing. If no return between −30% and 30% closes the gap, the calculator says there is none rather than reporting a bound as an answer.
$300 a month against an $8,000 card at 19%
An $8,000 balance at 19% APR with a $200 required payment, $300 a month in question, an assumed 7% annual return, 15% tax on gains, and a ten-year horizon. Paying the debt first clears it in month 19 for $1,299.15 of interest, then invests $500 a month for the rest of the horizon. Counting the part of month 19's payment the debt no longer needed, that is $50,700.85 contributed, $18,180.81 of gains, $2,727.12 of tax, and $66,154.54 of net worth.
Investing first pays only the $200 required and invests $300 a month. The card takes until month 64 to clear and costs $4,773.54 in interest — $3,474.39 more. That path ends with $47,226.46 contributed, $17,936.46 of gains, $2,690.47 of tax, and $62,472.45 of net worth.
Debt first ends $3,682.09 ahead. The break-even return on these inputs is 19.75% a year — above the card's 19% APR, because the gains are taxed at 15% while the interest avoided is not. Setting the tax to zero, as in a sheltered account, brings the threshold down toward the APR itself.
What this calculator assumes
- The APR and the assumed return are both fixed for the whole horizon; returns arrive as a steady monthly rate rather than as real market sequences.
- Both paths spend the identical amount every month for the identical number of months, and are scored on the same date.
- The required payment is a fixed dollar amount. A real card minimum falls as the balance falls, which would slow the invest-first path further.
- Investment contributions are made at the end of each month, with no fees, commissions, or dividends modeled separately.
- Tax is applied once, to gains only, at the horizon. A loss is not credited against other income.
- No employer match, no emergency fund, and no new borrowing are modeled. Money values are rounded to the nearest cent for display.
Understanding the Pay Off Debt or Invest Calculator
Every spare dollar has two obvious homes: the balance you owe, or the account you invest in. Clearing a balance earns exactly the APR written into your credit agreement, with no uncertainty at all — it is the only guaranteed return most people can access. Investing might earn more; it might earn less; and unlike the APR, nobody has promised anything. This calculator does not resolve that for you. It shows what the arithmetic says under an assumption you supply, and it names the assumption at which the two paths tie.
Both paths spend identical dollars for identical months and are scored on the same date, on the same measure: investments after tax, minus any debt still outstanding. Anything less strict lets one path win by running longer or by leaving a balance out of the total.
Who this calculator is for
- Anyone with spare cash and a balancewho wants the arithmetic before the argument.
- People with a low-rate loana student loan or a car loan, where the answer genuinely might be to invest.
- People with a high-rate cardwho want to see how far the assumed return has to stretch to beat it.
- Anyone weighing a tax-sheltered accountwho wants to see the same comparison with the tax on gains set to zero.
- Couples who disagree about itwho want one measure — net worth on one date — instead of two arguments.
Why it matters
- It compares like with like: identical monthly outlay, identical horizon, and one measure that carries both the investments and the remaining debt.
- It reports the break-even return — the assumed rate at which the two paths land level — which is the single number that makes the trade-off legible.
- It shows the tax on gains explicitly, because interest avoided is untaxed and investment gains usually are not. That asymmetry moves the break-even point above the APR.
- It carries any debt left at the horizon into net worth, so investing never looks free.
- It refuses to recommend. The APR is contractual and the return is a guess; the page shows both arithmetics and leaves the risk judgement where it belongs.
How to use this calculator
- Enter the debt's balance, its APR, and the payment your lender requires. The required payment is made on both paths.
- Enter the extra amount each month. That, and only that, is the money actually in question.
- Enter the annual return you want to assume. It is an assumption, not a forecast — try a pessimistic one as well as an optimistic one.
- Under advanced assumptions, set the horizon and the tax rate on gains. Set the tax to zero to model a sheltered account.
- Read which path ends ahead, by how much, and the break-even return that separates them.
How to read your result
The headline is the gap in net worth at the horizon: investments after tax, minus whatever debt remains. Both paths pay the same amount every month, so the gap is caused entirely by the order the dollars were spent in. Below it, the break-even return is the more durable insight — it is the assumed annual return at which the two paths land level, and it barely moves when you change the horizon. If your honest expectation sits below it, the debt path wins on these inputs; if it sits above, investing does.
Notice that the break-even usually sits above the debt's APR rather than exactly on it. That is the tax on gains doing its work: interest avoided is not taxed, so an investment has to out-earn the APR by enough to cover the tax before it pulls ahead. Set the tax rate to zero — modeling a sheltered account — and the threshold drops back toward the APR. And if the invest-first path still shows a balance at the horizon, read its net worth carefully: that debt is subtracted, which is why a strategy that leaves debt behind cannot win on a balance sheet just by holding assets.
- The APR is contractual; the return is a guess. Treating them as comparable numbers is the most common error this calculator can encourage, and the reason the break-even figure exists.
- Real returns are not smooth. A steady monthly rate is modeled here; actual markets deliver the same average through sequences that can leave you far from the projection at any particular date.
- An employer match is not modeled. Money matched at 50% or 100% is a return no consumer APR competes with, and it usually belongs before either path here.
- An emergency fund is not modeled either. Without one, a setback puts the spending back on the card at the same APR you were trying to escape.
- Tax is applied once, to gains, at the horizon. Real tax depends on the account type, the holding period, your bracket, and where you live.
- The debt's minimum payment is treated as fixed. A credit card minimum falls as the balance falls, which slows the invest-first path further than modeled.
- Run the comparison twice, at a pessimistic and an optimistic return. If the answer is the same both times, the decision is easy; if it flips, you have learned what the decision actually rests on.
- Set the tax rate to zero to see the sheltered-account version of the same question — the break-even usually drops noticeably.
- Check the break-even against the debt's APR. When the APR is high, the required return is often higher than anything a diversified portfolio has delivered on average.
Frequently asked questions
Should I pay off debt or invest?
That depends on a number nobody knows: the return your investments will actually deliver. What the arithmetic can say is where the line falls. This calculator computes the break-even annual return — the assumed rate at which both paths reach the same net worth — so you can compare it against your own expectation and your own tolerance for risk. It does not make the choice.
Why is the break-even return higher than my debt's APR?
Because interest avoided is untaxed while investment gains generally are not. To beat a 19% APR after a 15% tax on gains, an investment has to earn meaningfully more than 19%. Set the tax rate to zero, modeling a sheltered account, and the break-even falls back toward the APR.
How are the two paths made comparable?
Both spend the same total each month for the same number of months, and both are scored on the same date. The measure is investments after tax minus any debt still outstanding. Without both halves of that measure, a path that simply held onto debt would look richer than one that cleared it.
Does the debt-first path invest at all?
Yes. Once the balance is gone, the entire monthly amount — the former debt payment plus the extra — is invested for every remaining month. That is what makes the comparison fair: the debt-first path is not sitting in cash after the payoff.
What about an employer match on retirement contributions?
It is not modeled here, and it usually outranks both paths. A 50% match is an immediate 50% return on the matched portion, which no ordinary consumer APR competes with. Capture the match first, then use this page for the money left over.
Is this investment advice?
No. It is arithmetic on inputs you supply. FigureBetter is not a licensed adviser, does not know your circumstances, and does not recommend either path.
Are my inputs saved or shared?
No. Every calculation runs in your browser; nothing is stored on our servers or sent to analytics. A shareable link only encodes the numbers you choose to share.
The rest of the decision
If the answer here is to pay the debt down, the extra payment calculator prices exactly what that buys, and the snowball vs. avalanche calculator decides which balance it should attack when there is more than one. To work from a date instead, use the debt-free date calculator. For the investing half on its own, the compound interest calculator projects contributions without the debt beside them.
Sources and review notes
- U.S. Securities and Exchange Commission, Investor.gov — compounding and contribution growth
- Consumer Financial Protection Bureau — Debt
Methodology last checked Jul 28, 2026. Both paths and the break-even search are covered by deterministic unit tests, including negative assumed returns, a required payment that never clears the balance, and the case where no supported return closes the gap. No financial professional review is claimed yet.