If you have multiple debts — a credit card here, a personal loan there, maybe a 0% deal creeping toward its end date — you face a decision that personal finance enthusiasts argue about with remarkable intensity: do you pay them off smallest first, or highest-interest first? These two approaches have names. They have fan bases. And they genuinely produce different outcomes depending on your specific debts.
Let's settle this properly with some actual maths rather than vibes.
The Debt Snowball Method
The snowball method, popularised by US personal finance author Dave Ramsey, tells you to list your debts from smallest balance to largest and attack them in that order. You make minimum payments on everything, then throw every spare pound at the smallest debt until it's gone. When it's cleared, you take the money you were putting at it and add it to the next smallest debt. Your payment "snowballs" as each debt is eliminated.
The psychological logic is solid. Eliminating a debt quickly provides a tangible win. Wins feel good. Feeling good keeps you going. The snowball method doesn't optimise mathematically — it optimises behaviourally. For people who've previously tried and failed to pay off debt, momentum matters more than maths.
The Debt Avalanche Method
The avalanche method is the mathematician's choice. List your debts from highest interest rate to lowest and attack them in that order, regardless of balance size. Minimum payments on everything, maximum firepower at the most expensive debt. When it's cleared, redirect everything to the next highest-rate debt.
Because you're eliminating your highest-interest debt first, you pay less total interest over the repayment period. The avalanche saves money. Potentially a lot of money. The only downside is that the first debt to target might have a large balance — meaning it takes a while before you get that satisfying elimination moment.
How Much Difference Does It Make?
Here's a worked example. Imagine you have three debts:
- Credit card: £3,000 at 24% APR
- Personal loan: £6,000 at 8% APR
- Store card: £500 at 35% APR
You have £400 per month to put toward all three debts combined.
With the snowball method, you'd tackle the store card first (smallest balance), then the credit card, then the personal loan. With the avalanche method, you'd tackle the store card first anyway (highest rate), then the credit card, then the personal loan. In this case, both methods happen to agree on the order — the store card is both the smallest and the most expensive.
But change the numbers slightly — give the credit card a lower balance than the loan but a higher interest rate — and the methods diverge. Use our loan payment calculator to model each debt's monthly cost and remaining term, giving you the numbers you need to compare strategies.
Running the Numbers
On average, across typical consumer debt profiles, the avalanche method saves somewhere between £500 and £3,000 compared to the snowball method. The gap depends entirely on the spread between interest rates and the size of balances — the wider the rate difference between your debts, the more the avalanche wins.
For high-interest credit card debt specifically, use our credit card payoff calculator to see exactly how long a balance will take to clear under different monthly payment scenarios, and how much total interest you'll pay.
A useful rule of thumb: if all your debts have similar interest rates, the snowball's psychological advantages might outweigh the modest mathematical difference. If you have one debt at 30%+ (credit cards, store cards, overdrafts) sitting alongside debts at 5-10%, the avalanche wins by enough margin to be worth the motivation challenge.
The Hybrid Approach
You don't have to pick a lane rigidly. A reasonable hybrid strategy is to follow the avalanche method mathematically, but if a small-balance debt is close to elimination, knock it out quickly even if it's not the highest rate. The psychological boost costs relatively little and can help sustain momentum.
Equally, if you have a 0% deal with a looming end date, prioritise that debt regardless of both balance and rate — the rate it's about to revert to may be the highest in your portfolio and the window to clear it cheaply is finite.
What Actually Matters Most
The honest truth is that the best debt repayment method is the one you stick to. A snowball you follow consistently will always beat an avalanche you abandoned after month three. If you've tried to pay down debt before and motivation was your problem, snowball. If you're analytical, motivated by knowing you're optimising, and comfortable with a slow start, avalanche.
If debt has become overwhelming, StepChange offers free debt advice and can help you create a structured repayment plan regardless of which method you choose. They're excellent and judge-free.
One More Thing: Minimum Payments Are Not a Strategy
Whichever method you choose, the key ingredient is making more than minimum payments. Minimum payment calculators reveal something genuinely alarming: a £2,000 credit card at 24% APR, paid at the minimum every month, takes over 16 years to clear. The total interest paid exceeds the original balance multiple times over. Snowball or avalanche — it doesn't matter which you pick. Just make sure you're making real progress each month.