Debt payoff calculator — avalanche vs snowball
Order several debts by interest rate or by balance, add whatever you can spare, and see which order clears them sooner.
Debt free in
2.9 years
35 payments, 4,811 of it interest
- Interest paid
- $4,810.90
- Total repaid
- $30,511
- Saved vs snowball
- $171.59
| Debt 1 — 21.9% | month 21 |
|---|---|
| Debt 2 — 7.5% | month 35 |
| Debt 3 — 18.5% | month 25 |
On these three debts, attacking the 21.9% card first saves several hundred in interest against clearing the $3,200 card first.
Side by side
How this is calculated
Both strategies pay every minimum
Each month every debt gets its minimum, then everything spare goes to one target. Avalanche targets the highest rate; snowball targets the smallest balance. The difference is only the order.
spare = extra + Σ minimums of cleared debtsCleared minimums roll forward
When a debt clears, its minimum joins the spare pot rather than being spent. Clearing the $3,200 card frees its $80 minimum, so the next target receives $380 a month instead of $300. Without that rolling, both strategies are just minimum payments with a small top-up.
Worked example: Three debts, $300 a month spare
| Card | $8,500 at 21.9% |
|---|---|
| Personal loan | $14,000 at 7.5% |
| Second card | $3,200 at 18.5% |
| Order | 21.9% card, then 18.5%, then loan |
|---|---|
| Debt free in | about 3.6 years |
| vs snowball | a few hundred less interest |
Snowball clears the $3,200 card about eight months sooner, which is the entire argument for it — a visible win early, at a small cost in interest.
What this assumes
- No new spending on any of the debts.
- Rates stay fixed for the whole plan.
- Minimum payments stay flat, not tapering.
- Every payment is made on time.
Where this commonly goes wrong
- Card minimums normally fall as the balance does, which stretches the payoff far beyond what a flat minimum suggests.
- A 0% balance-transfer promotion beats both strategies while it lasts, but deferred-interest deals charge the whole accrued amount if any balance remains at the end.
- Spending on a card during the plan resets the maths entirely — the calculation assumes the balances only go down.
Questions
Is avalanche or snowball better?
Avalanche always costs less interest, because it kills the most expensive debt first. Snowball clears an individual debt sooner, which some people need to keep going. If the interest gap between your debts is small, the behavioural argument usually wins.
How much difference does the order actually make?
Less than most people expect. Across typical consumer balances the two strategies usually differ by a few hundred in interest and a month or two. The extra payment you add matters far more than the order you pay in.
Should I consolidate instead?
Consolidation helps when the new rate is genuinely lower and the term is not much longer. A lower monthly payment stretched over seven years often costs more in total than the debts it replaced, even at a lower rate.
What about a 0% balance transfer?
It beats any payoff order while the promotional period runs, as long as you clear the balance before it ends. Check whether it is a true 0% or a deferred-interest deal, which retroactively charges everything if a balance remains.
Do I keep paying minimums on everything?
Yes. Missing a minimum triggers fees, penalty rates and credit-file damage that dwarf any interest saved by redirecting the money. Every strategy here pays every minimum and only redirects the surplus.
Should I pay debt or build savings first?
Keep about a month of expenses as a buffer, then attack debt above roughly 8%, then finish the buffer. Without any buffer, the next unexpected bill goes straight back onto the card you just cleared.
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Sources
This calculator does arithmetic on the figures you enter. It does not account for tax, fees, or your personal circumstances.
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