The honest answer isn't "always avalanche" — it depends on whether you'll actually stick with the plan for the next 18 months.
The avalanche method orders debts by interest rate, highest first, and pays minimums on everything else. Mathematically it always saves the most total interest, because you're eliminating your most expensive debt first.
The snowball method orders debts by balance, smallest first, regardless of interest rate. It usually costs slightly more in total interest — but it produces a paid-off account faster, often within the first month or two.
| Method | Optimizes for | Best for |
|---|---|---|
| Avalanche | Lowest total interest paid | People who stay motivated by the math, not the wins |
| Snowball | Fastest first "debt eliminated" moment | People who need an early win to keep going |
Research on behavior change (and honestly, most people's real experience) points the same direction: debt payoff is less a math problem than a consistency problem. The method that keeps you paying every single month for a year-plus beats the technically-optimal method you abandon in month four. That's the entire case for snowball — it's a motivation tool disguised as a payoff strategy.
Most debt calculators show you a payoff date and stop. But debt payoff isn't a one-time calculation — it's a habit you have to repeat for months. The plans that actually finish are the ones where people track the streak, not just the balance: did I make the extra payment this month, did I skip the impulse buy, did I log my spending. A payoff plan with zero habit tracking is a spreadsheet. A payoff plan with a visible streak is something you don't want to break.