Debt Snowball Calculator
Pay debts smallest balance first — how long the whole set takes, what it costs in interest, and when each one clears.
The snowball orders debts by balance, smallest first, and throws every spare dollar at the front one while paying minimums on the rest.
How the debt snowball calculator works
The snowball orders debts by balance, smallest first, and throws every spare dollar at the front one while paying minimums on the rest. As each clears, its payment rolls into the next, so the amount attacking the debt grows.
It is not the cheapest method — the avalanche is — but it clears accounts fastest, and the completed-account effect is why it keeps people going. The calculator shows both the time and the extra interest so the trade is explicit.
Formula: order by balance ascending; roll each cleared payment into the next
Worked examples
| Inputs | Time to clear everything | Note |
|---|---|---|
| Three debts, 300 extra | 2 years 10 months | smallest first |
| No extra payment | 4 years 10 months | minimums only — far slower |
| A bigger extra | 1 year 9 months | cuts the time sharply |
FAQFrequently asked questions
What is the debt snowball?
Paying the smallest balance first regardless of interest rate, then rolling its payment into the next.
Is it the cheapest method?
No — the avalanche, which targets the highest rate first, always costs less or the same. This page shows exactly how much less.
Why does anyone use it then?
Because clearing a whole account early is motivating, and a method people finish beats a cheaper one they abandon. The research on this is genuinely mixed.
How much does it cost?
Usually modest — a few hundred over a few years for typical consumer debt. If the gap here is large, the avalanche is worth the discipline.
What if the minimums do not cover the interest?
Then the balance grows and no schedule clears it. The calculator says so rather than returning a number.
Where these figures come from
- CFA Institute — Quantitative Methods: The Time Value of Money — the discounting, annuity and IRR conventions used here
- US Federal Reserve — Regulation Z (Truth in Lending), APR calculation — why APR includes fees where a nominal rate does not
- ASIC MoneySmart — the Australian regulator's own consumer calculators
Last checked: September 2026. These are the standard textbook formulas; the conventions named are those of the CFA Institute curriculum and ISO 80000 usage.