There's a mathematically correct answer to "which debt should I pay off first" — and a behaviorally correct one. They're not always the same debt, and picking the wrong one for your actual situation can cost you the whole plan.
Two ways to order the same debts
Both strategies work the same basic way: pay the minimum on every debt, then throw every extra dollar at one target debt until it's gone, then roll that payment into the next one. The only difference is which debt you target first.
- Snowball targets the smallest balance first, regardless of interest rate.
- Avalanche targets the highest interest rate first, regardless of balance size.
A real example
Take two debts: a $1,000 balance at 8% APR with a $50 minimum, and a $5,000 balance at 22% APR with a $150 minimum. You can put $200 extra toward debt each month. Snowball attacks the $1,000 balance first, even though it carries the lower rate. Avalanche attacks the $5,000 balance first, even though it's larger, because 22% is the more expensive debt to be carrying.
| Strategy | Months to debt-free | Total interest paid |
|---|---|---|
| Snowball | 18 | $1,036.95 |
| Avalanche | 18 | $925.39 |
In this case, both strategies clear all debt in the same 18 months — but avalanche does it for $111.56 less in total interest. That gap isn't huge here because the balances are fairly close in size, but it scales up sharply with larger balances, bigger rate gaps, or longer payoff timelines.
Why avalanche almost always wins on paper
Interest accrues on whatever balance is sitting there, at whatever rate applies to it. Eliminating your most expensive debt first means less total interest accrues over the life of the payoff plan, full stop — it's the same logic as paying down the highest-APR balance on a credit card statement before a lower-APR car loan.
Why snowball still works for a lot of people
The math isn't the whole story. Snowball clears entire debts faster when balances vary a lot in size — that $1,000 balance in the example above would likely disappear in just a few months under snowball, giving you a real, visible win early in the plan. Avalanche, by contrast, might have you grinding on the same large balance for a year or more before anything actually closes out.
How to decide
- If your balances are similar in size but your rates vary a lot, avalanche's interest savings will be more meaningful — lean avalanche.
- If you have one or two small balances mixed in with larger ones, and you know you need quick wins to stay motivated, snowball's faster early payoffs may matter more than the extra interest.
- If you're not sure, run both — the gap between them tells you how much the "correct" answer actually costs, which is often smaller than people assume.
The Debt Snowball vs. Avalanche Repayment Planner runs both simulations side by side on your actual balances, rates, and minimums, so you can see the real dollar gap for your specific situation instead of a generic example.