Should you move a card balance to a 0% deal — or keep paying where it is? This tool runs both paths month by month at the same monthly payment: keeping the card, versus transferring (fee added on day one, intro APR, then the post-intro APR). It shows months to clear, total interest and total cost for each path, then the net saving and the break-even point where the fee would eat the whole saving. Everything runs in your browser.
| Path A · Keep the card | Path B · Transfer | |
|---|---|---|
| Starting balance | — | — |
| Months to clear | — | — |
| Total interest | — | — |
| Transfer fee | — | — |
| Total cost (interest + fee) | — | — |
| Total you pay overall | — | — |
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How it works: each month, interest accrues at APR ÷ 12 on the balance, then your payment is applied (the final payment is smaller — just enough to clear the balance). Path B starts from your balance plus the fee, charges the intro APR for the intro months, then the post-intro APR. Both paths are capped at 600 months; a payment that does not cover the monthly interest can never clear the balance and is flagged instead of faked.
Keep the card or take the transfer deal — months to clear, total interest and the net saving, month by month.
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Run both paths month by month at the same payment — keeping your current card, versus transferring the balance (fee added on day one, intro APR, then the post-intro APR) — and see months to clear, total interest, total cost, the net saving and the break-even fee where the deal stops paying.
A $6,000 balance at 24.99% APR with a $300 monthly payment takes 27 months to clear on the current card and costs $1,841.44 in interest (interest accrues monthly at APR ÷ 12, then the payment is applied — the closed-form term is 26.14 full payments plus a small final one). Transferring it at a 3% fee adds $180 on day one, making $6,180; twelve interest-free months cut that to $2,580, and at the same 24.99% post-intro APR it clears in 22 months total with $293.20 of interest. Total transfer cost is $293.20 + $180 = $473.20 against $1,841.44, a net saving of $1,368.23 and debt-free five months sooner. The deal would stay worth it up to a fee of $1,548.23 — the interest saving itself.
Each path is a monthly amortisation: interest for the month is the balance × APR ÷ 12, added to the balance, then the payment is applied, with the final payment capped at what is owed. Path A always uses your current APR. Path B starts from the balance plus the fee (balance × fee %), charges the intro APR for the intro months, then the post-intro APR. Both paths stop at 600 months; a payment that does not exceed the monthly interest can never clear the balance and is reported as “payment too low” rather than extrapolated. Net saving is Path A total cost minus Path B total cost (interest plus fee); the break-even fee equals the interest saving, because at that fee the two total costs are equal.
It is worth it when the interest you avoid is bigger than the fee you pay. This calculator makes that exact comparison: if the net saving line is positive, the deal pays on your numbers. The break-even line shows how much headroom you have — a fee well below the break-even fee means the deal wins comfortably.
The fee — typically 3–5% of the amount transferred — is added to the balance on the new card on day one, so you start owing the balance plus the fee. At a 0% intro APR that larger starting balance costs nothing extra while the intro lasts, which is why a fee can still be worth paying.
Any balance left when the intro ends starts accruing interest at the post-intro APR, which is often as high as the card you left. The calculator models exactly that: the win comes from clearing (or mostly clearing) the balance during the intro months, so compare the months-to-clear figure with the intro length.
If your monthly payment is less than one month of interest, the balance grows instead of shrinking and never clears. On a $6,000 balance at 24.99% APR, the first month of interest alone is about $124.95, so a $100 payment can never work — the tool flags that honestly instead of inventing a finish date.
Use the rate printed in the offer if you have it — that is the rate any leftover balance will actually face. The field follows your current APR by default because many cards revert to a similar rate, but the offer documents are the better source.
No. Every calculation runs in your browser on the numbers you type; nothing is sent to or stored on the server.
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