Debt avalanche calculator
Add each of your debts — balance, interest rate and minimum payment — plus an extra amount you can pay each month, and see your debt-free date, the total interest you will pay and the exact payoff order. It is for anyone juggling credit cards, store cards and loans who wants a clear, fastest-and-cheapest plan to get out of debt.
How it works
The tool simulates your debts month by month. In each month it:
- Accrues interest on every open balance: balance × (annual rate ÷ 100) ÷ 12.
- Pays the minimum on each debt.
- Directs the leftover budget (freed-up minimums plus your extra) at the single priority debt.
The priority debt is chosen by your strategy: avalanche targets the highest interest rate first (cheapest overall), while snowball targets the smallest balance first (fastest wins). When a debt is cleared, its minimum rolls into the next one. The simulation repeats until every balance reaches zero.
Example
Three debts paid with £150 extra per month, avalanche order:
| Debt | Balance | Rate | Min/mo |
|---|---|---|---|
| Store card | £1,200 | 29.9% | £40 |
| Credit card | £4,000 | 22.9% | £100 |
| Car loan | £8,000 | 6.5% | £180 |
Avalanche attacks the store card (29.9%) first, then the credit card (22.9%), then the car loan (6.5%) — paying off the highest-rate balances first to minimise the interest accrued along the way. The result panel shows the debt-free timeline and total interest for this plan.
These figures are estimates for guidance only and run entirely in your browser — nothing is uploaded.