How it works
Each month, interest is added to every card and each card receives a minimum payment (1% of the balance plus that month’s interest, at least £25). The rest of your budget goes to one target card: the highest APR (avalanche) or the smallest balance (snowball).
A worked example
With £2,500 at 24.9%, £1,200 at 19.9% and £600 at 29.9%, a £300 monthly budget clears the debt sooner and with less interest by paying the 29.9% card first.
What to keep in mind
Simplified model: monthly interest at APR ÷ 12, no new spending, fees or promotional rates, and a common minimum-payment rule. Card providers calculate minimum payments differently.
Which credit card should I pay off first?
To pay the least interest, pay the minimum on every card and put every spare pound towards the card with the highest interest rate. This is called the avalanche method. When that card is cleared, move its payment to the card with the next-highest rate.
Avalanche versus snowball
The avalanche method targets the highest APR and almost always costs the least. The snowball method targets the smallest balance first, which costs a little more but clears individual cards sooner, which some people find motivating. This calculator shows both so you can see the difference in pounds.
Consider a 0% balance transfer
If your credit score allows it, moving balances to a 0% balance transfer card can save more than either method. Check the transfer fee, usually 2% to 4%, and plan to clear the balance before the 0% period ends.
Always pay at least the minimum
Missing a minimum payment can mean late fees, a higher interest rate and damage to your credit file. Set up a Direct Debit for at least the minimum on every card, then pay the extra to your target card.
Frequently asked questions
Should I pay off the highest interest or the smallest balance first?
Paying the highest interest rate first (avalanche) saves the most money. Paying the smallest balance first (snowball) clears cards sooner but usually costs more interest.
How is the minimum payment calculated?
This calculator uses a common rule of 1% of the balance plus that month’s interest, with a £25 minimum. Your card provider’s rule may differ; check your statement.
Can I enter only two cards?
Yes. Set the third card’s balance to 0.
Does it include new spending?
No. It assumes you stop using the cards while paying them off.
For general information and planning, not personalised financial or tax advice. Verify important decisions with a qualified adviser.