Debt guides
Use this balance transfer calculator to test whether moving a credit card balance to a lower-rate or 0% offer is genuinely cheaper than staying where you are. The important question is not just whether the headline rate looks good. It is whether the transfer fee, promotional window, monthly payment and follow-on APR still leave you better off once the whole repayment plan is modelled.
Decision one
A transfer fee is not automatically bad. Paying a 3% fee to avoid many months of high card interest can be sensible, but the fee needs to be compared with what your current card would charge if you kept repaying at the same pace.
The calculator separates the cost of staying put from the cost of transferring so you can see whether the offer is a real saving or just a more comfortable-looking repayment route.
Decision two
The safest balance transfer is one where your fixed monthly payment clears the transferred balance before the 0% period ends. If a balance remains, the post-promo APR matters much more than the advertising headline.
Testing the payment you can actually afford is more useful than testing the payment you hope to make. A tight plan can fail after one expensive month.
Decision three
Sometimes the simplest answer is not a new card. If paying an extra amount on your current card removes most of the interest cost, applying for a transfer may not be worth the admin, eligibility check or fee.
If the current APR keeps the balance expensive even after overpaying, a transfer becomes more compelling, provided you can avoid new spending on the card.
Before you calculate
A balance transfer is often marketed around the longest 0% period or the lowest fee, but the best choice depends on your repayment behaviour. A shorter offer with a low fee can beat a longer offer if you will clear the balance quickly. A longer offer with a higher fee can be better if it gives you enough time to repay without relying on unrealistic monthly amounts.
Before entering figures, decide whether you are trying to reduce total interest, lower monthly pressure, or create a fixed deadline. Those are different goals. Someone with a stable budget and one high-APR card may prioritise the lowest total cost. Someone whose payments keep drifting may benefit more from a clear monthly target and an offer end date.
The mistake to avoid is assuming 0% means free. The transfer fee is normally added to the balance, which means you repay it as part of the plan. If you transfer £4,000 with a 3% fee, the cost is £120 before any post-promo interest appears. That may still be much cheaper than leaving the same balance on a card charging a high APR, but it should be measured rather than guessed.
Also think about payment allocation and new spending. A clean transfer plan keeps the moved balance separate and avoids fresh purchases on the same card unless the card terms are clear and favourable. Mixing old debt and new spending can make statements harder to read and can weaken the discipline that made the transfer useful in the first place.
Use the calculator in three passes. First, model your current card. Second, model the balance transfer using the payment you can maintain every month. Third, increase or decrease the transfer payment to see how sensitive the saving is. If a small payment change turns a good result into a poor one, the plan is more fragile than it first appears.
Calculator
Enter your current card details and the transfer offer to compare the saving, transfer fee and payoff position.
Your estimated saving, fee and payoff comparison will appear here after calculation.
Calculate to compare the transfer against staying on your current card.
Calculate to see whether the transfer fee is outweighed by the interest saved.
After you calculate
The result should be read as a repayment comparison, not as a product recommendation. A positive saving means the transfer is cheaper under the assumptions entered, but it does not automatically mean the card is right for you. Eligibility, credit limit, fees, minimum payment rules and your ability to avoid new borrowing still matter.
If the result shows a large saving and the balance clears during the promotional period, the transfer has a clear financial case. If the saving is small, the decision becomes more practical. You may decide the admin and credit check are not worthwhile, especially if a higher payment on the existing card produces a similar outcome.
If the balance remains after the 0% period, look closely at the follow-on APR. A transfer can still save money, but the remaining balance becomes exposed to standard card interest. That is where people get caught: the offer solved the first part of the problem but did not create a full repayment plan.
The monthly payment is usually the strongest lever because it decides how much balance is left when the promotional period ends. The fee matters most when the balance is repaid quickly. The follow-on APR matters most when the balance remains large after the offer ends. Change one input at a time so you can see which factor is carrying the result.
Write down the monthly payment needed to clear the balance before the promotion ends. If that payment is affordable in an ordinary month, the transfer is easier to justify. If it is not, compare a longer offer, a lower fee, or a separate debt repayment plan before applying.
Compare next
The right answer may be a balance transfer, but it may also be a fixed overpayment or a wider consolidation plan. Compare the realistic alternatives before choosing one route.
A transfer is strongest when the current APR is high, the fee is modest, the credit limit is large enough, and your monthly payment clears most or all of the balance inside the promotional period.
If increasing the payment on the current card removes most of the interest cost, a transfer may add unnecessary complexity. This is more likely when the balance is smaller or close to being cleared.
If several debts are involved, a single transfer may not cover the full problem. Consolidation can provide structure, but it must be checked against total interest and the risk of rebuilding card balances.
FAQ
No. The fee, the length of the promotional period, the post-promo APR and your monthly payment decide the outcome. A 0% offer can be poor value if the fee is high and the balance would have been cleared quickly anyway.
Many providers add the fee to the transferred balance. This means the fee becomes part of the amount you repay. Check the card terms because a fee charged upfront would affect cash flow differently.
The remaining balance normally moves onto the card’s standard APR. That can reduce the saving, especially if the remaining balance is large. This is why the post-promo APR should not be ignored.
Usually it is cleaner not to. Purchases may have different rates or payment allocation rules, and new spending makes it harder to track whether the transfer plan is actually reducing debt.
A full application normally involves a hard credit search. Eligibility checkers may use soft searches first, but approval, credit limit and rate are not guaranteed until the provider confirms them.
Use a fixed payment you can make in a normal month. If you only use an optimistic payment, the result may show a saving that depends on a plan you cannot maintain.
Last updated: