Credit Card Payoff Calculator
See exactly how long it will take to clear your credit card debt, how much interest you will pay, and how a balance transfer or extra payments could save you money. Includes FCA persistent debt thresholds and multi-card snowball vs avalanche comparison.
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How to Use This Calculator
Payoff Calculator tab
Enter your current balance, the APR from your card statement, and how much you plan to pay each month. The calculator shows how many months until the balance reaches zero, the total interest you will pay, and how that compares to making only the minimum payment. If your payment does not cover the monthly interest charge, the balance will grow and the debt will never be cleared — increase your payment until the calculator shows a payoff date.
Balance Transfer tab
Enter your current balance, your existing APR, and the terms of a 0% balance transfer offer: the interest-free period (in months) and the transfer fee (typically 1.5-3.5% in the UK). Add your monthly payment. The calculator tells you the minimum monthly payment needed to clear the balance inside the 0% window, the total cost with the transfer (fee plus any post-period interest), and how much you save versus staying on your current card.
Multiple Cards tab
Enter up to five credit cards — each with its balance, APR, and minimum payment — plus how much extra you can put towards debt each month. The calculator runs both the avalanche method (extra payment on highest-APR card first) and the snowball method (extra payment on smallest balance first), showing time to debt-free and total interest for each. Use the strategy selector to highlight the result that matters most to you.
Share your result
Every input is encoded in the URL. Click Share to send your exact scenario to a debt adviser, partner, or save it for later. Click Copy result to copy the full breakdown to your clipboard.
The Formula
Credit card interest compounds monthly. Each month, interest is added to the balance before your payment is applied:
Monthly Interest = Balance × (APR ÷ 12 ÷ 100)
Balance after payment:
New Balance = Previous Balance + Monthly Interest − Payment
UK minimum payment (standard formula):
Minimum Payment = Max(£25, Balance × 1% + Monthly Interest)
Months to pay off (algebraic shortcut when payment is fixed):
Months = −ln(1 − (Monthly Rate × Balance ÷ Payment)) ÷ ln(1 + Monthly Rate)
Total interest:
Total Interest = (Monthly Payment × Months) − Original Balance
The formula assumes a fixed monthly payment. In practice, UK credit card minimum payments reduce as the balance falls, which is why minimum-only repayment takes so long and costs so much in interest.
Example
Emma — Nurse, 31, Manchester
Emma has a £5,000 balance on her Barclaycard at 23.9% APR. She has been paying the minimum (around £80/month) and barely making a dent. She wants to know what happens if she increases her payment to £150/month, and whether a balance transfer makes sense.
Scenario 1: Pay £150/month
Scenario 2: Balance transfer (0% for 24 months, 3% fee)
If Emma pays £215/month on the balance transfer card, she clears the debt in exactly 24 months and pays only £150 in fees — saving £1,688 in interest versus continuing at minimum payment plus boosting to £150/month. The key: she must not miss payments and must clear the balance before the 0% period ends.