Balance Transfer Calculator
See how much you save by transferring credit card debt to a 0% intro APR card.
What this calculator does
This balance transfer calculator works out whether moving credit card debt to a 0 per cent deal is worth the transfer fee. Enter your balance, the APR you are paying now, the fee percentage, the length of the promotional period, and your monthly repayment, and it returns the interest avoided, the fee in pounds, and the net saving.
It simulates both cards month by month rather than holding the balance static, so the interest avoided reflects a debt that shrinks as you repay it. The monthly table shows both balances side by side — the transferred balance falling in a straight line, the old one dragged down by interest.
When to use it
The obvious case is a large balance on a high-rate card with a 0 per cent deal available. But the calculation matters most when the answer is close: a 3.5 per cent fee on a 12-month deal is a very different proposition from a 2.9 per cent fee on 21 months, and the difference is not obvious until you see the net figure.
It is equally useful as a reality check on whether you can clear the balance inside the window. Set the monthly repayment to what you can genuinely afford rather than what would be ideal, and see where the transferred balance lands when the deal ends. Anything left reverts to the go-to rate.
Understanding the inputs
Balance is what you would move across. The transfer fee is charged as a percentage of that amount and is normally added to the transferred balance rather than billed separately, so the calculator starts the new card slightly above your old balance.
Current APR should be the purchase rate on your existing card, shown on your statement. Intro months is the promotional period, commonly 12 to 24 on UK deals. The monthly repayment is the lever that decides everything — the calculator applies it to both cards so the comparison is like for like.
How is this calculated?
Transfer Fee = Balance × Fee %. Interest Saved = Months × (Balance × Current APR / 12). Net Saving = Interest Saved − Transfer Fee.
A worked example
Take a £5,000 balance at 24.9 per cent APR moved to a 21-month 0 per cent deal with a 2.9 per cent fee. The fee is £145, giving a transferred balance of £5,145, which needs £245 a month to clear inside the window — and at that repayment it does clear, with nothing reverting to the go-to rate.
Staying put and repaying the same £245 a month would take 27 months and cost about £1,570 in interest. Across the 21-month promotional period the transfer avoids roughly £1,474 of interest, and after the £145 fee the net saving is about £1,329. The fee is recovered inside the first two months.
Limitations and assumptions
The calculator assumes the whole balance is accepted for transfer, no new spending on either card, and no missed payments. Issuers frequently approve a lower limit than requested, which changes the arithmetic materially.
It does not model what happens if the balance is not cleared in time, nor the loss of the 0 per cent rate that a missed payment can trigger under most UK card agreements. If you are transferring repeatedly to stay ahead of a balance you cannot clear, free debt advice from StepChange or Citizens Advice is a better next step than another transfer.
Common Questions
- How much does a balance transfer cost?
- Most UK 0 percent transfer deals charge a one-off fee of around 1 to 3.5 percent of the amount moved, added to the balance immediately. On £5,000 that is £50 to £175. A few cards offer fee-free transfers, usually with much shorter 0 percent windows, so compare fee and window length together.
- What happens when the 0% period ends?
- Any remaining balance moves to the standard purchase rate, commonly 24 percent APR or higher. There is no taper. Divide the transferred balance plus the fee by the number of 0 percent months, and treat that as your minimum monthly payment for the whole period rather than paying the card's own minimum.
- Why is the card's minimum payment not enough?
- Because minimum payments are designed around the standard rate, not the promotional window. Paying the minimum on a £5,000 transfer with a 21-month deal typically leaves several thousand pounds outstanding when the 0 percent ends, at which point interest starts on the whole remainder. Set up a fixed standing order instead.
- Will I definitely get the advertised 0% period?
- No. Under FCA rules the advertised terms need only be offered to 51 percent of accepted applicants, so you may be given a shorter window, a smaller limit, or both. Use a soft-search eligibility checker before applying — it shows your likely acceptance odds and terms without leaving a hard search on your file.
- Can I transfer between cards from the same provider?
- No. Issuers do not permit transfers within their own group, and some brands share a banking licence even when the cards look unrelated. Check who actually issues both cards before applying, since a rejected transfer after acceptance leaves you holding a new card and the original balance.
- Does a balance transfer affect my credit file?
- The application leaves a hard search visible for a year, and the new account lowers your average account age. Against that, the extra credit limit reduces your overall utilisation, which Experian, Equifax, and TransUnion all treat positively. Keeping the old card open, at zero balance, generally leaves your file stronger than closing it.
- Should I spend on a balance transfer card?
- No. Purchases usually sit outside the 0 percent deal and attract the standard rate, and while UK payment allocation rules direct payments to the highest-rate balance first, that can mean your payments clear the purchases while the transferred balance sits untouched. Use a separate card for spending.
- Is a 0% money transfer different from a balance transfer?
- Yes. A money transfer moves cash from the card into your current account, which lets you clear an overdraft or a loan rather than another card. Fees are higher, typically 3 to 4 percent, and the 0 percent windows are shorter, but it is the only way to use card credit against non-card debt.
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