Enter your debts and one extra monthly payment. See exactly when you'll be debt-free with the snowball vs the avalanche method — and what each one costs in interest.
The calculator runs a month-by-month simulation of your actual debts. Each month it applies interest (APR ÷ 12), pays every minimum, then directs your entire extra payment at one target debt — the highest-rate debt for the avalanche, the smallest balance for the snowball. When a debt is cleared, its minimum payment rolls into the attack budget (that's the "snowball" effect, and it applies to both methods). The result is the honest number most debt calculators hide: the same debts, the same money, two different orders — and the real difference in months and interest.
Interest compounds on whatever you leave for last. Clearing a 24% APR credit card before a 6% loan can save hundreds or thousands over the payoff — that's the avalanche's edge. But behaviour matters as much as maths: research on debt repayment consistently finds people are more likely to stick with a plan that produces early wins. If the avalanche only saves you a small amount, the snowball's momentum may be worth more than the maths.
Whichever you choose, the real engine is the extra payment — and that comes from your budget. A zero-based budget, where every unit of income gets a job before the month starts, is how most people find the extra money in the first place. Try our zero-based budget calculator to see where yours could come from.
Every month, for each debt: interest = balance × APR ÷ 12. Then every minimum payment is made, and all the money left over from your monthly budget (the extra payment plus the minimums of debts you have already cleared) goes to one target debt. The avalanche targets the highest APR; the snowball targets the smallest balance.
Three debts and $200 a month extra:
| Debt | Balance | APR | Minimum |
|---|---|---|---|
| Store card | $600 | 12% | $30 |
| Credit card | $4,000 | 24.9% | $100 |
| Personal loan | $6,000 | 6% | $150 |
| Method | Time to debt-free | Total interest | Order cleared |
|---|---|---|---|
| Avalanche | 25 months | $1,306.26 | Credit card, store card, loan |
| Snowball | 25 months | $1,380.75 | Store card, credit card, loan |
Same time, and the avalanche saves $74.50 of interest. When the difference is that small, the snowball's early win from clearing the small card first can be worth more than the money.
With the snowball method you pay minimums on every debt, then put all extra money toward the smallest balance first. When it is paid off, its payment rolls into the next smallest. It usually costs slightly more in interest than the avalanche method, but the quick early wins help many people stay motivated.
With the avalanche method you pay minimums on every debt, then put all extra money toward the debt with the highest interest rate first. Mathematically this is the cheapest and fastest way out of debt — it minimises the total interest you pay.
Avalanche saves the most money; snowball gives faster psychological wins. This calculator shows you the real difference in pounds/dollars and months for your actual debts. If the difference is small, pick snowball for the motivation. If it is large, the avalanche is worth the patience.
No. Everything is calculated in your browser on this page. Nothing is sent to any server, and nothing is stored after you close the tab.
The avalanche costs less interest because it clears the highest-rate debt first. The snowball clears the smallest balance first, which gives quick wins that help some people keep going. If the calculator shows a small difference for your debts, choose whichever you will stick with.
A common approach is a small starter emergency fund first, so a surprise does not become new debt, then high-interest debt, then a full emergency fund. Use the emergency fund calculator to size the starter fund. This is general information, not financial advice.