Credit Card Interest Calculator
See exactly how much interest a credit card balance costs — and how much longer it takes — if you pay only the minimum instead of a fixed monthly amount. Enter your balance, APR and payment to compare both.
Check your card's representative APR on your statement.
Months to clear at your payment
27 mo2.3 years · total interest £916
Months to clear on minimum only
600+ mo50.0+ years · total interest £13,510
The minimum-payment trap costs you
£12,594 extra interest
and 573 extra months by paying only the illustrative minimum instead of £150/month.
| Strategy | First payment | Months | Total interest | Total paid |
|---|---|---|---|---|
| Minimum only (illustrative) | £75 | 600+ | £13,510 | £16,510 |
| Fixed £150/month | £150 | 27 | £916 | £3,916 |
Minimum payment illustrated as the greater of 2.5% of the outstanding balance or £5 — a representative shape only. Your card issuer sets its own minimum in your credit agreement; check your statement for the actual figure.
At this rate, minimum payments alone may never clear the balance
Interest is accruing faster than the minimum payment reduces the balance — the debt can grow indefinitely. Consider a 0% balance transfer card, a fixed payment well above the minimum, or free debt advice from StepChange or National Debtline.
How Credit Card Interest Works
If you clear your statement balance in full each month, most UK credit cards charge no interest at all — that's the interest-free period. Once you carry a balance past the due date, interest is charged on the outstanding amount at your card's APR, and it compounds: next month's interest is calculated on a balance that already includes last month's unpaid interest.
The gap between paying the minimum and paying a fixed amount above it compounds too — a small increase in your monthly payment can cut years off the payoff time and save hundreds or thousands of pounds in interest, because more of each payment goes toward the balance rather than interest.
Worked Example
£3,000 balance at 24.9% APR
- Fixed £150/month — months to clear
- 27 months
- Fixed £150/month — total interest
- £916
- Minimum only — months to clear
- 600+ months
- Minimum only — total interest
- £13,510
- Extra interest from the minimum-payment trap
- £12,594
Minimum payment illustrated as the greater of 2.5% of the outstanding balance or £5 — a representative shape, not a fixed industry rule. Check your own card's credit agreement for the actual minimum.
Getting Out of Credit Card Debt Faster
0% Balance Transfer
Moving your balance to a 0% purchase or balance transfer card pauses interest for a promotional period (commonly 12–30 months), usually for a one-off transfer fee. Every pound you pay goes straight to the balance while the 0% period lasts — set a fixed monthly payment large enough to clear it before the promotional rate ends.
Pay More Than the Minimum
Even a modest increase above the minimum meaningfully shortens the payoff time, because more of each payment reduces the principal rather than covering interest. Use the calculator above to compare a few payment amounts and see the effect on your own balance.
Budget the Difference
Free up room for a higher fixed payment by working through your outgoings with the budget planner — it can also be used as an income and expenditure form if you need one for a creditor or debt adviser.
Free Debt Advice
If minimum payments alone aren't keeping pace with interest, free and independent advice is available from StepChange, National Debtline, and MoneyHelper.
Frequently asked questions
How is credit card interest calculated?
UK credit card providers charge interest daily or monthly on your outstanding balance, based on your card's APR (Annual Percentage Rate). If you don't clear the balance in full each statement, interest is added on top — and unless your payment exceeds the interest charged, the balance keeps growing. This calculator applies your APR as a monthly rate (APR ÷ 12) to project the balance forward.
What is the minimum-payment trap?
Card issuers set a minimum payment — often the greater of a small percentage of the balance (illustrated here as 2.5%) or a £5 floor. Paying only the minimum keeps you technically compliant, but because most of a low minimum payment goes on interest rather than the balance, it can take decades to clear a card this way and cost several times the original balance in interest.
What counts as a typical UK minimum payment?
There's no single legal formula — each provider sets its own minimum in the credit agreement. A common shape is the greater of roughly 1%–3% of the balance or a small fixed floor (often around £5). This calculator uses 2.5% / £5 as an illustrative default; check your own statement or credit agreement for the actual figure that applies to your card.
Does a 0% balance transfer help?
Yes, if you can qualify and pay it off within the promotional period. Moving a balance to a 0% purchase or balance transfer card (usually for a fee of a few percent) pauses interest accrual entirely for the promotional term, so every pound you pay goes toward the balance instead of interest. Set up a fixed monthly payment sized to clear the balance before the 0% period ends, or you'll revert to the card's standard APR on whatever remains.
How much would £3,000 at 24.9% APR cost on minimum payments vs a fixed £150/month?
On a £3,000 balance at 24.9% APR: paying a fixed £150/month clears the balance in 27 months (2.3 years) with £916 total interest. Paying only the illustrative minimum takes 600+ months and £13,510 in interest — an extra £12,594 and 573 months compared with the fixed payment.
Sources
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