Debt Snowball vs Avalanche: Which Wins? 1,000-Profile Study (2026)

The snowball method (smallest balance first) vs avalanche method (highest APR first) debate gets recycled monthly on r/personalfinance with dueling assertions and zero data. We simulated 1,000 realistic multi-debt profiles to put numbers on it.

Finding 1: Avalanche wins on interest in 70.3% of profiles

The mathematical claim is well known — paying highest-APR first minimizes total interest. The data confirms it with a clean margin: 703 of 1000 profiles finished cheaper under avalanche, with a median savings of $556 in interest. 1 profiles finished cheaper under snowball — almost always when the highest-balance debt also happened to be the highest-APR debt (the orderings coincide).

Finding 2: The interest gap is smaller than the internet pretends

Median gap of $556 is real but not life-changing — about 4–8% of typical total interest paid. The 90th-percentile gap of $8,066 only shows up in profiles with a high-APR balance hiding behind several large low-APR balances (the worst case for snowball).

Practical implication: if behavioral momentum matters to you (closing accounts feels good, you've quit debt-payoff plans before), the $556 median gap is a reasonable price for not quitting. If you're disciplined and your highest-APR debt is also your largest, the methods are nearly indistinguishable anyway.

Finding 3: Snowball-winning profiles have lower weighted APR (10.0% vs 13.0% overall)

The 1 profiles where snowball matched or beat avalanche on total interest share a pattern: their weighted-average APR is 10.0% — lower than the overall pool average of 13.0%. When all your debts are cheap (auto + student loans, no credit cards), the ordering barely matters and small-balance-first can win by clearing minimum payments faster, which compounds into the cascade.

Sample profiles (10 evenly spaced by total debt)

Methodology

• 1,000 profiles, each containing 2–6 debts.
• Debt mix per profile: 45% credit card (APR 18–30%, balance $500–$10,000), 25% auto (6–11%, $4,000–$25,000), 15% student (4.5–8.5%, $5,000–$40,000), 15% personal (9–16%, $2,000–$20,000). Modeled on FRB G.19 and NY Fed HHDC averages.
• Minimum payment: 2% of balance, floor $25.
• Extra monthly payment: 5–40% on top of total minimums (uniform).
• Snowball ordering: lowest balance first. Avalanche ordering: highest APR first.
• Cascade rule: when a debt is cleared, its minimum payment is added to the next debt's extra (the "snowball" effect — applies to both orderings).
• PRNG: Mulberry32, seed 20260523. Reproducible build-to-build.
• Excluded: new charges, late fees, balance transfers, debt consolidation, income shocks, payment skips.

Limitations

• Behavioral persistence is not modeled. The biggest claim of the snowball method — that early wins prevent quitting — cannot be captured in a deterministic simulation.
• APRs are static. Promotional APRs that expire (very common on credit cards) would shift the math toward avalanche.
• Minimum payments are a flat 2% of balance. Real minimums often have a fixed-dollar floor plus a percentage of new charges.
• No new charges. Profiles where someone keeps spending on a card while paying it off behave very differently.

Frequently asked questions