Both strategies require the same monthly commitment. They only differ in which debt gets the extra money. The math says avalanche always wins on dollars saved. The psychology says snowball wins on consistency.
The Debt Avalanche
Pay minimums on every debt. Throw every extra dollar at the debt with the highest interest rate. When it's gone, roll its payment into the next highest. Repeat until done.
Best for: people motivated by numbers, comfortable with delayed gratification, and likely to stick with a plan that pays off in mathematical efficiency rather than visible progress.
Pros: Saves the most interest. Mathematically optimal. Always faster than snowball when debts have different rates.
Cons: If your highest-rate debt is also your largest, you might not see any debt eliminated for a long time. This can sap motivation.
The Debt Snowball
Pay minimums on every debt. Throw every extra dollar at the debt with the smallest balance regardless of interest rate. When it's gone, roll its payment into the next smallest.
Best for: people who get discouraged by long timelines, who haven't successfully stuck with a debt plan before, or who simply value the visible wins of crossing debts off the list.
Pros: Quick wins build momentum. One debt eliminated in the first month or two. Research (Kellogg, HBR) shows higher completion rates than avalanche.
Cons: Mathematically suboptimal. Pays more total interest. The difference is usually a few hundred to a few thousand dollars over the life of the plan.
The Hybrid Approach
Some people knock out one or two small debts first for momentum (snowball), then switch to avalanche for the rest. This captures most of the psychological benefit of snowball while still saving most of the interest of avalanche. There's no rule. The best strategy is the one you'll actually finish.
When the Strategies Converge
If your smallest debt also has the highest interest rate, both strategies target the same debt first and produce nearly identical outcomes. Run both in the calculator above and compare the side-by-side results.