EyeOnWhat this type of product does
A balance transfer moves debt from one credit account to another, usually to a card offering a low or zero interest rate on transferred balances for a limited period. The saving comes from the difference in interest while the debt is being paid down.
Availability, transfer limits and fee structures vary by country and change frequently. Nothing here names a provider. The point is a comparison method you can apply to whichever offers are in front of you.
The numbers to line up side by side
The transfer fee is usually a percentage of the amount moved and is the single biggest variable between offers. A 0% period with a 3% fee can cost more than a short low-rate period with no fee, so compare the total expected cost, not just the headline rate.
Work out what you could realistically repay each month, then check whether the promotional period covers that timeline with a margin. If the balance would still be large when the standard rate starts, that end rate matters more than an extra month or two of 0%.
Details that often hide in the small print
Check whether the fee is charged upfront or added to the balance, what happens to new spending on the card — many cards charge standard-rate interest on purchases while a transfer sits on the account — and whether the promotion is lost if a payment is late.
Some providers also set a transfer deadline, limit the amount that can be moved, or exclude certain debts. Payment allocation rules between balances, purchases and fees affect how quickly the expensive parts are cleared, and are worth reading before assuming a figure.
A simple way to decide
Estimate the total cost of each offer you are considering: transfer fee plus any interest before the balance would be cleared. Include your own likelihood of making the payments on time. The cheapest offer on paper is rarely the cheapest offer for the way someone actually behaves.
A transfer that only slows the debt is not a saving. Pair the comparison with a repayment plan — for example the approach in the balance transfer calculator — and keep the old account open briefly if closing it would change your credit utilisation.