Home › Calculator Hub › Snowball vs Avalanche
Decision ToolEnter up to three debts and your total monthly budget. The calculator runs both strategies side-by-side and shows the extra interest the snowball costs you (if any) — the price of behavioural simplicity.
Runs entirely in your browser — your numbers are never sent to a server.
Snowball wins behaviourally if:
Avalanche wins mathematically when:
A 2016 Harvard Business School study found snowball produced higher completion rates in real-world debt elimination programmes. The authors concluded that debt elimination feels more like running a marathon than solving a maths problem — early wins matter.
Many debt advisers suggest: use snowball for your first 1-2 small debts to build momentum, then switch to avalanche for the rest. Captures most of the psychological benefit at a small cost in interest.
It depends on your APR spread. If all debts are 15-20% APR, the cost difference is minimal. If you have a 29% card AND a 6% loan, avalanche saves meaningfully.
Speak to a free debt adviser — StepChange, National Debtline, Citizens Advice. Do not take new credit before getting advice.
Not usually. Mortgages are long-term, secured and typically lowest APR. Target unsecured debt first.
Illustrative calculation. Not personalised financial advice. Rates, bands and allowances for the 2026/27 UK tax year, verified against gov.uk at time of review. For regulated advice consult an FCA-authorised adviser.