Debt avalanche

Definition

The debt avalanche method targets the highest interest rate first while you make minimum payments on other debts. When that balance clears, the extra payment moves to the next-highest rate. The idea usually minimises total interest compared with smallest-balance-first (snowball), all else equal — same minimums, same extra cash, same starting balances.

Avalanche is an ordering rule for existing debts. It does not change your contractual rates, and it is not the same as refinancing or consolidating into a new product. Those moves need separate break-even checks because fees and new terms can erase the interest saving avalanche was aiming for.

How it works

1. List every debt with its balance, interest rate and minimum payment.
2. Decide a fixed monthly budget that is more than the sum of the minimums.
3. Pay every minimum, then send all the spare money to the debt with the highest rate.
4. When that debt clears, add its old minimum to the spare money and point the lot at the next-highest rate. The payment “rolls” down the list, which is where the name comes from.

The total you pay each month stays the same throughout. Only the order changes, so any difference between avalanche and snowball is purely the interest saved by shrinking the dearest balance sooner.

Why avalanche matters for personal loans

Interest compounds on whatever balance remains. Paying extra against the dearest rate first stops the most expensive balance growing (or shrinking slowly) while cheaper balances tick along on minimums. For a mix of cards at high APR and a lower-rate personal loan, avalanche often points extra cash at the cards first — unless behaviour risk means you will abandon the plan without an early win.

Avalanche also clarifies what consolidation must beat. If avalanche already directs extras at the costly balances, a consolidation loan only helps if the blended rate, fees and term beat that path on lifetime cost — not merely on the new monthly instalment.

Worked EXAMPLE — when avalanche and snowball differ (checked Oct 2026)

All figures below are labelled EXAMPLE. They are illustrative only — not a live quote and not a credit offer. They come from this site’s own payoff maths, with interest charged monthly at the annual rate divided by twelve.

Three debts: a store card of £900 at 9.9% (minimum £30), a credit card of £4,200 at 24.9% (minimum £110) and a loan of £3,100 at 14.9% (minimum £95). Minimums total £235, and there is £100 EXAMPLE extra each month, so £335 goes out every month either way.

• Avalanche targets the 24.9% credit card first, then the loan, then the store card. Everything is cleared in 33 months with about £2,230.03 of interest EXAMPLE.
• Snowball targets the £900 store card first, then the loan, then the credit card. Everything is cleared in 34 months with about £2,781.61 of interest EXAMPLE.

Avalanche saves about £552 and one month here EXAMPLE. The reason is simple: under snowball the £4,200 card sits on its minimum at 24.9% while spare money clears a balance charging 9.9%. Raise the extra to £150 a month and the gap stays similar: about £1,798.22 against £2,337.98 of interest, and 27 months against 28 EXAMPLE.

Worked EXAMPLE — when the two methods agree

Now use the three-debt EXAMPLE from the snowball page: £1,200 @ 29.9% EXAMPLE, £3,400 @ 22.0% EXAMPLE, £6,800 @ 9.9% EXAMPLE, plus £75 EXAMPLE extra per month. Here the smallest balance also has the highest rate, so both methods pick the same order and give the same result: 48 months and about £3,349.28 of interest EXAMPLE. Avalanche only beats snowball when the two orders differ.

To see months and interest side by side on your own labelled inputs, use the snowball vs avalanche calculator. The guide snowball vs avalanche walks through behaviour versus maths without turning either method into advice.

Common confusions

• Ranking by balance size instead of rate (that is snowball).
• Ignoring promotional 0% periods that expire mid-plan; rank by the rate that will apply.
• Treating avalanche as a way to pay less each month. It is not; it changes the order, not the monthly total.
• Assuming you will stick with avalanche if early wins matter for motivation.
• Skipping fee checks when replacing avalanche with a consolidation loan.

UK context

Avalanche is a rule for ordering spare money between debts you are already keeping up with. It is not a rule for deciding which bills to pay when money is short. MoneyHelper’s guide to managing credit well says the debt to clear first is likely to be the one with the highest interest rate, while still paying at least the minimum on everything else, and that debts secured on your home should be paid first because the consequences of not paying are much worse.

Its guide on how to prioritise your debts explains that priority debts, such as rent, mortgage, Council Tax and energy bills, are not necessarily the largest or the most expensive, but come first because of what can happen if they go unpaid. If you are falling behind, free debt advice is a better starting point than any payoff method.

How LoanCalc Lab uses it

Avalanche is always compared against snowball under identical assumptions so the only difference is payoff order. Results stay illustrative. Country mode does not change the ordering logic — only currency and labels.

What it is not

Avalanche is not personalised advice, not a guarantee you will stick with it, and not a substitute for free debt advice if you are struggling. LoanCalc Lab is not a lender. Last checked 26 October 2026.