0% Balance Transfer Calculator UK [2026] — Clear Debt Before the Promo Ends

A 0% balance transfer moves credit card debt to a new card charging no interest for a set promotional period, in exchange for a one-off fee (commonly around 2.9% in the UK). To find out if it's worth it, divide the transferred balance plus the fee by the number of 0% months to get the payment needed to clear it in time — then check that figure against what you can afford. This calculator shows that payment, the balance left over if you fall short, and the interest it would cost at the revert APR.

Your balance transfer

Balance to transfer

Balance transfer fee

Typical UK fee is 1–3%, usually added to the balance.

Promotional rate

Usually 0%. Change it for a low-rate (not 0%) promo.

0% months remaining

How long the promotional rate lasts.

Revert APR (after promo)

The rate on any balance left when the 0% ends.

Monthly payment you can afford

Your current card APR (for comparison)

The APR you'd pay if you stayed put and didn't transfer.

Results — your 0% transfer plan

Enter your figures above to see your plan.

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Payment to clear before the 0% ends

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Transfer fee

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Balance on new card (inc. fee)

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Left when 0% ends

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Total cost of the transfer

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Enter each figure above; the plan updates instantly as you type.

Transfer vs. staying on your current card

At your affordable payment	0% transfer	Stay put
Time to clear	—	—
Interest paid	—	—
Total paid (inc. any fee)	—	—

Balance over time

The shaded red zone shows the months after your 0% deal ends, when any remaining balance starts accruing interest at the revert APR.

Key takeaways

The fee is usually worth it — if you clear in time. A one-off 2–3% fee is far cheaper than a year of interest at 20%+, provided you clear the balance before the promo ends.
The revert rate is the trap. Anything left when the 0% expires jumps to the revert APR (often 21.9–24.9%). Set a reminder a month before the deadline to clear or re-transfer.
Divide balance-plus-fee by the 0% months to get the payment that clears it exactly on time. Falling short? Increase the payment or shorten the balance.
Fold it into your wider plan. Transfer your highest-APR debt to 0%, then attack the rest with the debt avalanche or debt snowball method.
Don't spend on the new card. Purchases usually aren't covered by the 0% deal and can attract interest immediately.

What is a 0% balance transfer?

A 0% balance transfer moves debt from one credit card to another that charges no interest for a fixed promotional window — often 12 to 30 months. In return you pay a one-off transfer fee, usually 1–3% of the balance, which most UK cards add straight onto the amount you owe. For the length of the promo, every pound you pay goes to clearing the balance rather than servicing interest, which is why it's one of the most powerful tools for getting out of expensive card debt.

The catch is the deadline. The 0% rate only lasts for the promotional period; after that, any remaining balance reverts to the card's standard APR — typically 21.9% to 24.9%. The whole strategy hinges on clearing the balance, or transferring it again, before that happens.

How to calculate if a balance transfer saves you money

The maths is a straight comparison: the transfer fee versus the interest you'd otherwise pay. Take a £3,000 balance on a card at 24.9% APR. Left where it is and paying £150 a month, it would cost you hundreds of pounds in interest and take well over two years to clear. Move it to a 0% card with a 2.9% fee and the fee is just £87 — after which every £150 payment reduces the debt directly.

To find the payment that clears the balance exactly on time, divide the transferred balance including the fee by the number of 0% months. For £3,000 plus an £87 fee (£3,087) over 18 months, that's about £171.50 a month. Pay that and you'll be debt-free with the promo, having paid £87 instead of hundreds in interest. The calculator above runs this comparison for your own numbers and tells you whether your affordable payment gets you there in time.

The revert-rate trap

The single biggest mistake with balance transfers is treating the 0% period as open-ended. It isn't. When the promotional window closes, any balance you haven't cleared starts accruing interest at the revert APR — and because that rate is usually north of 22%, a balance you were happily ignoring can suddenly become expensive overnight.

Protect yourself two ways. First, set a calendar reminder for one month before the promo ends so you have time to act. Second, have a plan for any leftover balance: either increase your payments in the final months, or line up another 0% transfer to move the remaining debt before the deadline. The calculator flags exactly how much would be left over and what it would cost you at the revert rate if you did nothing.

How balance transfers fit into the debt snowball or avalanche

A 0% transfer isn't a strategy on its own — it's a tool that supercharges one. The smart play is to transfer your highest-APR debt to 0%, which instantly removes your most expensive interest, then keep clearing the rest of your debts with a structured plan.

If you're motivated by quick wins, run the debt snowball, clearing your smallest balances first. If you want to pay the least interest overall, the debt avalanche targets your highest rates first — and a balance now sitting at 0% naturally drops to the bottom of that priority list until the promo nears its end. Either way, use our budget planner to find the extra cash that lets you clear the transferred balance before the deadline.

For the full playbook — choosing a deal, dodging the revert-rate trap, and the common mistakes that turn a saving into a cost — read our 0% balance transfer strategy guide.

Common mistakes to avoid

Spending on the new card. Purchases usually aren't part of the 0% deal and can start charging interest straight away.
Missing a payment. A single missed minimum payment can void the entire 0% offer, dumping you onto the revert rate early.
Only paying the minimum. Minimum payments won't clear the balance before the promo ends — you'll drift straight into the revert-rate trap.
Forgetting the deadline. Without a reminder, it's easy to let the promo lapse and lose the whole benefit.

When a balance transfer isn't the answer

Balance transfers aren't a fix for every situation. The best 0% deals need a good credit score, so if your credit is impaired you may be declined or only offered a short promo with a higher fee. If your balance is too large to realistically clear within any promo period, a debt consolidation loan with a fixed term may suit you better. And if the underlying issue is spending outstripping income, no transfer will solve it — the debt will simply rebuild on the old card.

If you're struggling to keep up with payments, speak to a free debt charity such as StepChange, National Debtline or Citizens Advice before taking on new credit. A government Breathing Space can freeze most interest and charges for up to 60 days while you get advice.

Frequently Asked Questions

How do I calculate if a 0% balance transfer is worth it?

Compare the transfer fee against the interest you'd otherwise pay. Multiply your balance by the fee percentage (e.g. £3,000 × 2.9% = £87). If the interest on your current card over the same period is more than that fee, the transfer saves money — provided you clear the balance, or move it again, before the 0% period ends and the revert APR kicks in.

What monthly payment do I need to clear my balance before the 0% ends?

Divide the transferred balance (including the transfer fee) by the number of 0% months remaining. For a £3,000 balance with a 2.9% fee (£3,087 total) and 18 months left, you need about £171.50 a month to be clear before the promotional rate expires. The calculator does this for you and warns you if your affordable payment falls short.

What is the revert rate on a balance transfer card?

The revert rate is the standard APR that applies to any balance still on the card once the 0% promotional period ends — typically 21.9% to 24.9% in the UK. Any balance you haven't cleared starts accruing interest at that rate, which is why clearing (or re-transferring) before the deadline matters so much.

Is the balance transfer fee added to my balance?

Usually, yes. Most UK cards add the transfer fee to the transferred balance rather than charging it separately, so a £3,000 transfer with a 2.9% fee becomes a £3,087 balance on the new card. This calculator adds the fee to the balance so your payment plan reflects the true amount owed.

Does a balance transfer hurt my credit score?

There's a small, short-term dip from the hard credit check when you apply, and opening a new account lowers the average age of your credit. But by cutting your interest and helping you clear debt faster, a balance transfer usually improves your credit profile over time as your utilisation falls. Avoid applying for several cards at once.

Can I spend on a 0% balance transfer card?

You can, but you usually shouldn't. The 0% deal typically covers transferred balances only — new purchases often attract interest immediately, and your payments may be applied to the cheapest debt first. Treat the card as a repayment vehicle, not a spending card, until the transferred balance is gone.

What happens if I can't clear the balance before the 0% ends?

Any remaining balance starts accruing interest at the revert APR (often 21.9%–24.9%). Your options are to transfer the remaining balance to another 0% card before the deadline, fold it into your debt snowball or avalanche plan, or increase your monthly payment now. Set a calendar reminder a month before the promo ends so the deadline never catches you out.

Disclaimer: This calculator is for informational purposes only and does not constitute financial advice. Results are estimates based on the figures you enter and assume a fixed payment, a fixed revert APR and interest compounding monthly. Actual card terms, minimum payments and interest calculations vary by provider. If you are struggling with debt, contact a free UK debt advice service such as StepChange (stepchange.org) or National Debtline. For personal financial advice, consult a qualified adviser regulated by the Financial Conduct Authority (FCA).