When someone has multiple debts - a credit card here, a car loan there, maybe a personal loan - one of the first questions is: which one do I pay off first?
Two strategies have become the most widely discussed answers to that question. They share the same core mechanics but differ in one crucial way: how they decide which debt gets your attention first.
The shared foundation
Both strategies start with the same principle. Each month, you make the minimum payment on every debt to stay current. Then, any extra money you can put towards debt goes entirely to one specific debt, your target.
When that target debt is fully paid off, something powerful happens: the money you were paying on it (both the minimum and the extra) rolls forward and gets added to your payment on the next target debt. This cascading effect means your payments get larger over time, accelerating the process as you go.
The only difference between the two strategies is how they pick which debt to target first.
The Debt Snowball
The snowball method targets the debt with the smallest balance first, regardless of interest rate. Once the smallest debt is gone, you move to the next smallest, and so on.
The logic is psychological. Clearing a debt entirely, even a small one, creates a sense of progress and momentum. That first win comes quickly, and the freed-up payment rolls into the next debt, making it fall faster too. Like a snowball rolling downhill, each payoff adds mass to your next attack.
How it looks in practice
In the example below, the Medical Bill (smallest balance at £800) gets targeted first, even though it has 0% interest. Watch how it's cleared quickly, and its minimum payment immediately rolls into the next smallest debt.
The Debt Avalanche
The avalanche method targets the debt with the highest interest rate first, regardless of balance. Once that debt is cleared, you move to the next highest rate.
The logic is mathematical. High-interest debt costs the most over time. Every month it accrues more interest than lower-rate debts. By eliminating the most expensive debt first, you minimise the total interest paid across the entire repayment period.
How it looks in practice
With the same debts, the avalanche method targets the Credit Card first (23.9% APR is the highest rate), even though it has a much larger balance than the Medical Bill. It prioritises eliminating the most expensive interest first, then moves to the Personal Loan (11.9%).
See them side by side
The real differences become clear when you see both strategies running on the same set of debts. The interactive tool below uses four sample debts and lets you adjust the extra monthly payment to see how it affects both approaches simultaneously.
Sample debts
Debt payoff projection
Snowball - Interest
£4,582
Avalanche - Interest
£3,771
Interest Difference
£810
Snowball - Timeline
3yr 4mo
Avalanche - Timeline
3yr 3mo
Time Difference
1mo
Snowball order (smallest first)
Avalanche order (highest rate first)
Key differences at a glance
| Snowball | Avalanche | |
|---|---|---|
| Targets first | Smallest balance | Highest interest rate |
| Optimises for | Quick wins and momentum | Lowest total interest paid |
| First payoff | Usually faster since small debts clear quickly | Can take longer if the high-rate debt has a large balance |
| Total interest | Typically higher | Typically lower |
| Psychological benefit | Early wins build confidence | Satisfaction of mathematical efficiency |
| Works best when | Motivation and consistency are the main challenge | Interest rates vary significantly between debts |
What matters most
The difference in total interest between the two strategies is often smaller than people expect, especially when the extra monthly payment is generous. In many real-world scenarios, the gap narrows to a few hundred pounds.
Research and financial commentary tend to agree on one thing: the strategy you stick with is the one that works. Both methods use the same rollover mechanics. Both accelerate over time. Both get you to the same destination: zero debt.
Some people find that quick wins keep them engaged. Others prefer knowing they're paying the mathematical minimum. The numbers differ slightly; the outcome depends on follow-through.