A snowball calculation sends extra payment to the smallest balance first. An avalanche calculation sends it to the highest APR first. Compare them using the same balances, rates, minimums and extra monthly amount. Deal with priority debts and urgent consequences before relying on either ordering model.
Put the same inputs through both orders
For every included debt, record the current balance, annual percentage rate and minimum monthly payment. Add only an extra payment you can reasonably sustain. The estimate applies monthly interest, pays required minimums and sends the remaining budget to the selected order until balances reach zero or the calculation limit is reached.
Compare estimated months and total interest. The result is sensitive to changing rates, fees, payment dates, lender allocation rules and new borrowing. It is not a settlement figure.
Check priority debts before optimisation
MoneyHelper distinguishes priority debts by the seriousness of the consequence, not simply balance or APR. Court fines, rent or mortgage arrears, council tax, energy and other priority obligations may require action before unsecured debts. Seek free independent debt advice when payments are being missed or consequences are serious.
The calculator should warn when a stated minimum does not cover the modelled monthly interest. That warning means the simplified schedule cannot produce a credible payoff route from the supplied numbers.
Are any debts priority debts or already in emergency status?
Stops an optimisation model overriding more serious consequences.
Are balances, APRs and minimums current?
Sets the minimum evidence for comparison.
Is the extra payment affordable and repeatable?
Prevents an attractive schedule being built from unavailable cash.
Does this situation require free independent debt advice?
Keeps high-consequence decisions with an appropriate adviser.
Read the estimate as a comparison
Avalanche will often reduce interest in this simplified model because expensive balances receive extra payment earlier. Snowball may clear a small balance earlier. Neither result establishes the best personal route, affordability, creditor treatment or legal consequence.
The Debt Payoff Plan stores the entered figures locally and displays both estimates. Do not enter account numbers or other unnecessary identifying data.
Frequently asked questions
The avalanche often does in a simplified model, but verify the result using current lender figures, fees and payment rules.
Do not let the calculator decide their treatment. Review priority consequences and seek independent advice where needed.
No. It is an estimate from the supplied inputs and simplified monthly-interest assumptions.
What private and pay once mean
Private means the downloaded tool needs no account and makes no network requests, so the publisher receives no copy of what you enter. The record stays in the current browser unless you export it. Browser storage and exported backups are not encrypted or protected from another person who can use the same browser profile or read the file.
Pay once means you may keep reusing the version you downloaded without a subscription. Future major versions and continuing support are separate unless they are explicitly included. There is no cloud sync: export a backup before clearing browser data or changing device.
Use the smallest useful tool
The method above does not require a purchase. If a retained local record would reduce repeated setup, review the relevant interactive tool after its tested release.