The Debt Snowball vs Avalanche Math: We Ran the Numbers
Two famous debt-payoff strategies: the snowball (smallest balance first) and the avalanche (highest APR first). One saves you more money. The other helps you actually finish. Here’s the real math.
Setup: Three Cards, $15,400 Total
- Card A: $1,200 balance at 26% APR
- Card B: $4,200 balance at 21% APR
- Card C: $10,000 balance at 17% APR
- Combined minimum payments: $310/month
- Budget available: $600/month total
The Snowball Path
Pay minimums on B and C; throw everything extra at A first (smallest balance).
- A clears in ~3 months
- B clears next, ~13 months from start
- C clears last, ~38 months from start
- Total interest paid: about $5,400
The Avalanche Path
Pay minimums on A and B; throw everything extra at C (wait, no — at A, which has the highest APR at 26%).
- A clears in ~3 months
- B clears next, ~14 months from start (slightly slower than snowball because B has lower APR than A but the gap is small)
- C clears last, ~37 months from start
- Total interest paid: about $5,150
So Avalanche “Wins” by $250 — Is That a Lot?
In a 38-month plan, $250 is less than $7 a month. Statistically meaningful but not life-changing.
Why Snowball Often Wins in Real Life
Behavioral finance research (notably from Northwestern’s Kellogg School) found that people who use the snowball stick with the plan longer because they get early wins — the dopamine of closing an account.
If avalanche-followers quit after 12 months when they’re still working on the same big balance, they end up paying more than snowball-followers who finished. The strategy you’ll complete beats the strategy that’s mathematically optimal on paper.
The Hybrid: APR-Filtered Snowball
A practical middle ground: ignore any debt below ~3% APR (federal student loans, 0% promos) — let them ride. Then sort the rest by balance (snowball) but jump to avalanche if any account has an APR more than 5 points above the next.
Bottom Line
If your debts have similar APRs (within 5 points), use snowball for the motivation. If one debt is much more expensive than the others (15%+ gap), use avalanche to attack it. Either way: pick one and stick with it.