Balance transfer calculator

The fee is a percentage of the total balance moved, held between any floor and cap you set and rounded to the smallest unit of the currency: fee = round(min(max(ΣB × fee%, floor), cap)). It is added to the new card, so the transferred balance is B′ = ΣB + fee. Both the fee and the balances sit at the promotional rate, which is how most issuers treat a transfer.

The transfer path then runs one month at a time. Each month charges interest on the opening balance at APR ÷ 12 (or (1 + APR)^(1/12) − 1 under the compounded convention), using the promotional APR up to and including the last promo month and the go-to APR from the next month on. The annual fee, if any, is added in months 12, 24 and so on. The payment is then taken, capped at the balance so the final month never overpays. The balance after the last promo month is reported as the amount left when the promo ends.

In clear within the promo mode the payment is the level annuity on B′ over the promo months at the promotional rate, rounded up: P = roundUp(B′ ÷ n) when the promo rate is 0. The schedule is simulated with that payment and, if rounding or an annual fee inside the window leaves anything owing, the payment is raised by the smallest amount that clears it, so the balance really is zero at the end of the promo.

The stay-put path hands the same cards, minimums and monthly amount to the engine behind the debt payoff calculator, in avalanche order: every minimum is paid first and the rest goes to the highest-APR card. If the amount entered is below the sum of the minimums, the stay-put path pays the minimums instead and says so. The saving is stay total paid − transfer total paid, where the transfer total includes every fee. Break-even is fee ÷ (Σ monthly interest on the current cards − monthly interest on B′ at the promo rate), a first-order figure that assumes the balances stay constant for the month, shown to one decimal place.

Full method, rounding and tests on the methodology page

The transfer fee is charged on the amount you move, typically between 1% and 5% depending on the market and the offer, sometimes with a minimum of a few units of currency and occasionally with a cap. Because it is added to the balance, a 3% fee on 6,000 means you borrow 6,180 from day one. In the United States the CFPB confirms that a fee can be charged even on a 0% offer, and Regulation Z requires any advertised promotional rate to state when it ends and what rate follows.

The promotional period is counted in months from the transfer and is the whole point of the exercise: every month inside it is a month of no (or low) interest on the full balance. US rules require a promotional rate to last at least six months unless a payment is more than 60 days late; UK offers commonly run for two years or more, with the fee rising as the period lengthens. The calculator uses whatever you type.

The go-to rate is the standard purchase or transfer APR the card reverts to once the promo expires. It is often as high as, or higher than, the rate you moved away from, which is why the figure to watch is not the saving in month one but the balance still owing when the promo ends. Our guide to how credit card interest works explains how that monthly charge is worked out.

The easiest mistake with a balance transfer is to treat the promotional period as the end of the story. In the worked example, 300 a month leaves 780.00 on the card after 18 months; at 200 a month it leaves 2,580.00. From the next month that residual is charged at the go-to rate, and if the payment is close to the interest it generates the balance can hang around for years. The calculator highlights the amount left when the promo ends, flags a payment that does not even cover the go-to interest, and shows the payment that would have cleared the balance in time.

Two other habits erode a transfer. New purchases on the promotional card are often charged at the full purchase rate and may not be covered by the promo, so the calculator assumes no new spending on any card. And missing a payment can end the promotional rate early under the card’s terms. In the United Kingdom, cards whose minimum payments have covered more interest and charges than balance over 18 months fall under the FCA’s persistent-debt rules, a reminder that a low rate only helps if the balance actually falls.

If a 0% card does not fit, the debt consolidation calculator prices a single fixed-term loan against the same cards, and the credit card payoff calculator shows what a fixed payment does to one card on its own. Our guide to debt consolidation loans compares the two routes.

The calculator opens with a 3% fee, an 18-month promotional period at 0% and a 24.9% go-to rate because those are typical of the offers advertised in several countries when this page was reviewed. They are editable starting points, not products, and DebtWren does not recommend or rank cards. The fee, the period, the go-to rate, any minimum or maximum fee, and the amount an issuer will accept are all set by the issuer and usually depend on a credit check. Many issuers also limit a transfer to a share of the new card’s credit limit and require it to be made within a set number of days of opening the account.

Type the figures from the offer you are actually looking at, including the fee floor or cap and any annual fee, and run the stay-put comparison with the amount you can genuinely afford each month. If two offers differ only in fee and promo length, run each in turn and compare the saving and the balance left when the promo ends; a longer promo with a higher fee is not automatically better.

Your numbers stay in your browser. DebtWren works out your results on your device. We don’t send the balances, rates or payments you type to our servers or store them. If you allow analytics, we record only broad ranges (for example “£2,000–£5,000 of debt”) to understand how the calculators are used. Like any website with ads, this page also loads advertising scripts; see our Privacy Policy.

The calculator is plain code running in this tab. It makes no network requests with your figures, and nothing is saved when you leave unless you choose to keep it. Read the privacy policy for how ads and analytics work on this site.

• CFPB — What is a balance transfer fee? Can a balance transfer fee be charged on a zero percent interest rate offer?
• CFPB — How long can I keep a low rate on a balance transfer or other introductory rate?
• CFPB — 12 CFR §1026.55: Limitations on increasing annual percentage rates, fees, and charges (Regulation Z)
• CFPB — 12 CFR §1026.16(g): Advertising promotional rates and fees (Regulation Z)
• FCA Handbook — CONC 6.7: Post-contract business practices (persistent credit card debt)

Estimates for general information only — not financial, credit or legal advice. Your actual figures depend on your lender’s or card issuer’s exact terms, fees, minimum-payment rules, interest calculation method and any changes they make. Check your statements and speak to a qualified adviser before making decisions. The fee, promotional period and go-to rate shown are editable examples, not offers; your issuer’s terms, credit limit and transfer deadline decide what you can move and what it costs.

Page reviewed October 9, 2026 by the DebtWren team · Methodology · Changelog · Report an error