Debt payoff calculator — snowball vs avalanche
Add your debts and see which payoff strategy gets you debt-free faster and cheaper.
Your debts by share of total
Or quick-add a common type (edit the details after):
On top of your £305 in minimum payments.
E.g. a bonus or tax refund put toward debt in a specific month.
Avalanche
Highest APR first
Debt-free in
3 yr
Total interest
£3,667
Snowball
Smallest balance first
Debt-free in
3 yr 1 mo
Total interest
£4,017
At minimum payments alone, at least one of these debts would never be paid off — its interest would keep outpacing the payment. Any extra you can add changes that; see the strategies above.
Avalanche saves you (vs. snowball)
£351
Avalanche order
- 1. Store card
- 2. Credit card
- 3. Car loan
Snowball order
- 1. Store card
- 2. Car loan
- 3. Credit card
Balance over time
Move across the chart to inspect any month.
Avalanche minimises total interest paid; snowball clears small debts first, which some people find more motivating even though it usually costs a bit more. Figures are estimates and assume a fixed interest rate and consistent payments. Your inputs are saved locally in this browser so you can come back to them.
Snowball vs avalanche: how each method works
Both methods put the same total amount toward debt each month — your minimum payments plus whatever extra you can afford. The only difference is which debt gets the extra money first, once minimums are covered.
Avalanche sends extra payments to the debt with the highest interest rate first, regardless of balance. Mathematically this is always the cheapest approach, because it stops the most expensive interest from accruing as early as possible.
Snowball sends extra payments to the smallest balance first, regardless of rate. It usually costs a little more in total interest, but clearing a whole debt sooner is motivating for a lot of people — and a payoff plan you actually stick to beats a theoretically optimal one you abandon.
How this calculator works
Each month, interest is added to every debt at its annual rate divided by 12. Minimum payments are then applied to every debt, and whatever budget is left over — plus any one-off payment due that month — goes entirely to whichever debt is highest-priority under the selected strategy. This repeats until every debt reaches zero. A promotional rate (like a 0% balance-transfer offer) is used instead of the standard APR for the number of months you specify, then the debt reverts to its normal rate automatically. A one-time fee (like a balance-transfer fee) is added to that debt's starting balance, so it's paid down — and accrues interest — along with the rest of what you owe.
Frequently asked questions
If your debts feel unmanageable — you're only able to cover minimums, or not even that — free, independent advice is available from StepChange, National Debtline, or Citizens Advice. They can help with options this calculator doesn't cover, like debt management plans, IVAs, or negotiating directly with creditors — and it costs nothing to talk to them.