Debt Snowball vs Avalanche Calculator

Compare the snowball and avalanche payoff methods across all your debts — payoff time and total interest, side by side.

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The two most popular debt payoff strategies attack the same problem in opposite orders. The debt snowball pays minimums on everything and throws every spare dollar at the smallest balance first — when it's gone, its minimum payment rolls into the next-smallest debt, building momentum and quick psychological wins. The debt avalanche instead targets the highest interest rate first, which is mathematically optimal: every dollar aimed at the most expensive debt eliminates the most future interest. This calculator runs both strategies on your actual debts. Enter up to five debts (balance, APR, and minimum payment for each — leave unused slots at zero) plus the extra amount you can pay beyond the minimums each month, and it simulates each method month by month: minimums are paid on every debt, the extra goes to the strategy's target debt, and freed-up minimums from paid-off debts snowball into the pool. The output shows time to debt-free and total interest under each method, side by side, along with the avalanche's dollar advantage. For most real debt mixes the avalanche saves money but the difference is smaller than people expect — often a few hundred dollars and a month or two — which is why the honest answer to 'which is better?' is: the one you'll stick with. If quick wins keep you motivated, the snowball's cost is usually modest; if you're strictly numbers-driven, the avalanche wins by construction.

How It Works

Both simulations follow the same monthly cycle on your real debt list. Each month, every open debt accrues interest (balance × APR ÷ 12) and receives its minimum payment. The extra payment — plus the minimum payments freed up by any already-eliminated debts — goes entirely to the strategy's target debt: the smallest remaining balance for the snowball, the highest APR for the avalanche. When a debt reaches zero, its minimum rolls into the pool from the following month, so your total monthly outlay stays constant while its focus shifts. The simulation runs until every balance reaches zero and reports months to debt-free and cumulative interest for each strategy. The avalanche can never lose this comparison mathematically — directing money at the highest rate always minimizes interest — but the gap depends on your specific mix: it's large when balances and rates are inversely ordered (big high-rate debts alongside small low-rate ones) and near zero when your smallest debts also carry the highest rates, making the two strategies choose the same targets. The model assumes fixed APRs, constant minimums, and no new borrowing.

Examples

Three typical debts, $200 extra per month
A $6,000 credit card at 24%, a $12,000 car loan at 7%, and a $20,000 student loan at 5.5%.
Result: Here the smallest debt is also the most expensive, so both methods target the credit card first and the results are identical — debt-free in 4 years 4 months with about $6,265 in interest either way.
When the methods disagree: small cheap debt vs large expensive debt
A $2,000 personal loan at 6%, a $9,000 credit card at 26%, and a $15,000 loan at 9%, with $300 extra.
Result: The snowball clears the $2,000 loan first for a fast win; the avalanche attacks the 26% card and saves about $725 in interest — both finish in just over 3 years.

Frequently Asked Questions

Which is better — snowball or avalanche?
Mathematically, the avalanche always wins or ties: paying the highest rate first minimizes total interest by construction. Behaviorally, research on debt repayment suggests people who see quick wins are more likely to persist — which is the snowball's whole design. The honest answer is that the best method is the one you'll actually follow for years. Run your real numbers in this calculator: if the avalanche's savings are small (often the case), the snowball's motivational advantage is cheap. If the savings are large — typically when your biggest debts also carry the highest rates in reverse order of size — the avalanche deserves the discipline.
What does 'rolling over' minimum payments mean?
When a debt is paid off, the money you were sending to its minimum payment doesn't return to your budget — it rolls into the payment on the next target debt. This keeps your total monthly debt outlay constant while concentrating increasing firepower on fewer debts, which is why payoff accelerates toward the end. Both the snowball and avalanche use rollover; they differ only in the order of targets. The rollover discipline matters more than the ordering: abandoning it (spending freed-up minimums) costs far more than choosing the 'wrong' strategy.
Should I include my mortgage or student loans?
Usually not the mortgage — its rate is typically far below consumer debt and the balance would dwarf the strategy comparison. This tool is designed for consumer debts: credit cards, personal loans, auto loans, medical debt, and private student loans. Federal student loans are a judgment call: their rates are often low and they carry income-driven repayment and forgiveness options that pure payoff math ignores. A common approach is to run the strategies on everything above ~6-7% APR and pay minimums on cheaper debt while investing the difference.
What if I can't afford anything beyond the minimums?
With zero extra payment, both strategies produce identical results — the rollover effect still applies once the first debt naturally pays off, but progress is slow. Before choosing a strategy, focus on creating any extra margin: even $50/month meaningfully changes the timeline at credit-card rates. Also consider rate reduction: a 0% balance-transfer card or debt consolidation loan lowers the interest drag while you build repayment capacity. If minimums themselves are unaffordable, contact a nonprofit credit counselor (NFCC-affiliated) before missing payments.
Does either method help my credit score faster?
They differ only slightly. Both keep every account current, which protects payment history. The snowball closes individual accounts faster (fewer accounts with balances is a modest positive), while the avalanche typically reduces total balances — and therefore overall credit utilization — slightly faster if the high-rate debts are credit cards. Utilization improvements show up in scores within a billing cycle or two, so the avalanche often has a small early-score edge when cards dominate the debt mix. In practice the difference is minor compared to the effect of steady on-time payments and falling balances under either method.

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