Reviewed by Mustafa Bilgic
Founder, WebCalculator
Interest calculations are simplified models. For personalised debt advice, contact StepChange (free). Not financial advice.
This debt repayment calculator compares the snowball and avalanche methods to pay off your debts. Enter up to three debts with their balances and interest rates, plus any extra monthly payment you can make, to see how many months each strategy takes and how much interest you save.
Up to 3 debts compared
Both strategies make the same minimum payments on all debts but differ in where the extra payment goes. The snowball targets the smallest balance first for quick wins. The avalanche targets the highest interest rate first to minimise total interest. Once a debt is cleared, its payment "rolls" into the next target — creating an accelerating payoff.
In practice, the interest difference between the two is often small (£50 to £300 on typical consumer debts). The psychological advantage of the snowball method — seeing debts disappear quickly — is why many debt charities recommend it. Choose whichever you can stick with.
Debt 1: £5,000 credit card at 22.9% APR
Debt 2: £2,000 personal loan at 18.9% APR
Debt 3: £800 interest-free buy-now-pay-later
Snowball order: Clear the £800 BNPL first (4 months), then the £2,000 loan, then the £5,000 card.
Avalanche order: Attack the 22.9% credit card first, then the 18.9% loan, then the 0% BNPL last.
Both strategies clear all debt in roughly the same time, but avalanche saves interest because the expensive card is paid down faster while interest accrues.
Balance transfers. A 0% balance transfer card can freeze interest on credit card debt for 12 to 28 months. This effectively turns every pound of payment into principal reduction. Factor the transfer fee (typically 1.5% to 3%) into your calculation.
Consolidation loans. If you can get a personal loan at a lower rate than your existing debts, consolidating simplifies payments and reduces interest. Be careful not to re-borrow on the freed-up credit cards.
Negotiate lower rates. Call your credit card company and ask for a rate reduction. If you have a good payment history, many issuers will lower your APR by several points rather than lose you as a customer. Even a 2% reduction on a £5,000 balance saves roughly £100 per year.
Round up payments. If your minimum is £47, pay £50. Small round-ups add up over months without being painful, and they reduce the principal faster.
If you are struggling, the breathing space scheme gives you legal protection from creditor action for 60 days. During this period, interest and charges are frozen, and creditors cannot contact you or take enforcement action. You can apply through a qualified debt adviser at StepChange or Citizens Advice. A mental health crisis breathing space lasts longer and can be extended by your care coordinator.
After breathing space ends, your debt adviser can help set up a formal debt management plan (DMP) with reduced payments based on what you can afford, or explore other options like individual voluntary arrangements (IVAs) or debt relief orders (DROs) for smaller debts under £30,000.
If you are struggling with debt repayments, free help is available. StepChange and National Debtline offer confidential advice on debt management plans (DMPs), individual voluntary arrangements (IVAs), and breathing space — a 60-day pause on enforcement action and interest. Never pay for debt advice in the UK.
Check your debt-to-income ratio to understand how lenders view your borrowing. The loan calculator shows total interest on a consolidation loan, and the savings goal calculator helps you build an emergency fund alongside debt payoff.
The snowball method means paying minimum payments on all debts except the smallest balance, which gets all your extra cash. When the smallest is cleared, its payment rolls into the next smallest, and so on. The psychological boost of quick early wins keeps motivation high, though you may pay slightly more interest than the avalanche method.
The avalanche method prioritises the debt with the highest interest rate first. You make minimum payments on everything else and throw all extra cash at the most expensive debt. This minimises total interest paid and is mathematically optimal, but the first debt may take longer to clear, which some people find demotivating.
Avalanche saves more money in interest. Snowball gives faster psychological wins. The best method is the one you stick with. Research suggests that the snowball method leads to higher completion rates because early wins build motivation. If your highest-rate debt is also your smallest, both methods are identical.
Even £50 to £100 extra per month can dramatically shorten your repayment timeline. The calculator shows the impact of different extra payment amounts. Before overpaying debt, ensure you have a small emergency fund of at least one month's essential expenses to avoid needing to borrow again if something goes wrong.
If your debt interest rate is higher than your savings interest rate, which is almost always the case for credit cards and personal loans, paying off debt first gives a guaranteed better return. The one exception is building a small emergency fund of £1,000 to £2,000 before aggressively attacking debt, to prevent re-borrowing.
Yes. Reducing your credit utilisation ratio, which is the percentage of available credit you are using, is one of the most impactful things you can do for your credit score. Keeping utilisation below 30% is ideal, and below 10% is excellent. Clearing debts also reduces your debt-to-income ratio, which lenders assess on mortgage applications.
Yes. StepChange, National Debtline, and Citizens Advice all offer free, confidential debt advice. They can help with debt management plans, individual voluntary arrangements and breathing space orders. If you are struggling to make minimum payments, contact a free advice service before taking on more debt.