Both methods do the same first thing: pay the minimum on every debt, every month, no exceptions. The only question is where the extra money goes. The avalanchesends every extra dollar to the highest-APR debt until it's gone, then to the next-highest, and so on. The snowball sends every extra dollar to the smallest balance instead — ignoring APR entirely — and rolls each cleared payment into the next-smallest once that debt is retired.
A concrete example
Suppose you have three debts and $200/month available above the combined minimum payments:
- Card A: $1,500 balance at 22% APR, $30 minimum
- Card B: $8,000 balance at 18% APR, $160 minimum
- Card C: $5,000 balance at 12% APR, $100 minimum
Total balance: $14,500. Combined minimums: $290/month. With the extra $200, your budget is $490/month until a debt clears, at which point that debt's minimum rolls into the next target.
| Method | Months to debt-free | Total interest | First debt cleared |
|---|---|---|---|
| Avalanche (22% → 18% → 12%) | 39 | $3,985 | Card A, month 8 |
| Snowball (smallest balance first) | 40 | $4,466 | Card A, month 8 |
Avalanche finishes one month earlier and pays about $481 less in interest. Notice that both methods clear Card A first — its $1,500 balance is the smallest and its 22% APR is the highest, so the two methods happen to agree on month one. They diverge after that: avalanche attacks Card B next (18% APR, $8,000) while snowball attacks Card C ($5,000, 12% APR). Snowball clears Card C around month 24, which feels like fast progress — but because $8,000 sat at 18% the whole time, total interest is higher when the dust settles.
The behavioral tradeoff
The avalanche always wins on math. That's not a judgment call — it's arithmetic. Any dollar diverted from the highest APR is, by definition, earning a lower interest rebate. But the snowball wins on something the math doesn't see: momentum. Clearing an entire debt — closing a tab in your financial life — is qualitatively different from watching a single balance shrink. It produces a visible win, often within the first few months, and visible wins keep people in the chair.
If you've started and stopped a payoff plan before, that's a strong signal the behavioral payoff matters for you. The snowball costs a few hundred to a couple thousand dollars on a mid-size portfolio. If that's the difference between finishing in three years and quitting after six months, take the deal. If you know yourself well enough to grind through 39 months on autopay without quitting, take the math.
When the gap is bigger — or smaller
The cost of choosing snowball over avalanche scales with two things: the APR spread between your debts and the balance inversion (small balance happens to have low APR, large balance happens to have high APR). If all your debts are within a couple of APR points of each other, the two methods finish within a month and a few dollars of each other — pick whichever you will actually do. If you have a $500 store card at 28% and a $20,000 car loan at 4%, the snowball would burn money for years to clear the small one first; the avalanche is clearly correct.
Run your own numbers
Both methods are implemented as calculators on this site using the same input format, so you can swap between them and watch the totals change. Enter your real debts and your real extra payment, and the difference will either be loud enough to take seriously or small enough to ignore.
- Debt Avalanche calculator — highest-APR-first, minimum total interest.
- Debt Snowball calculator — smallest-balance-first, fastest first win.
- Debt Consolidation calculator — compare both against rolling everything into a single new loan.