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Debt Payoff Calculator
Snowball vs avalanche, side by side — months to debt-free, total interest, interest saved, and a balance-transfer break-even. Accurate, instant and free — for United States.
What these mean:
What these mean:
Your debts
Paste a spreadsheet selection — 4 columns: name, balance, APR%, minimum payment. Existing rows are replaced.
Balance transfer analyser
Avalanche strategy: debt-free in 40 months, paying $6,065 total interest. You save $8,734 vs minimums only. First cleared: Card A (month 13). Avalanche (highest APR first) saves the most interest — snowball clears the first debt in 7 months but costs $473 more.
Remaining balance — with vs without
40 mosStrategy comparison
Neither strategy is universally right. Snowball builds motivational momentum by clearing small debts first; avalanche minimises total interest. Use the one you will stick to.
Snowball — motivation win
Month 7
Store card cleared first
41 months total · $6,538 interest
Avalanche — math win
$473 saved
Card A cleared first (month 13)
40 months total · $6,065 interest
Balance transfer break-even
Worth itTransfer fee
$150
Interest avoided
$1,437
Net saving
$1,287
Clear before
Month 15
Simple-model caveat: interest avoided is an upper bound — it assumes the full balance remains outstanding for the entire promo period at your current APR. As you make payments, interest accrues on a declining balance, so real savings will be somewhat lower.
How snowball and avalanche payoff is calculated
Every month, each debt accrues interest of balance × APR ÷ 12. You pay the minimum on every debt, then funnel all spare cash — your extra payment plus the minimums freed from cleared debts — into one target debt. The only difference between the two methods is which debt is the target: avalanche takes the highest APR, snowball the smallest balance. The math is currency-agnostic; APRs and balances are your inputs.
Avalanche
Highest APR first → least interest
target = max(APR)
- Attacks the most expensive debt first
- Mathematically minimises total interest
- The optimal choice on money alone
First win can be slower to arrive.
Snowball
Smallest balance first → momentum
target = min(balance)
- Clears a whole debt sooner
- Behavioral momentum → higher completion
- Costs a little more interest
The behavioral win, not the math win.
Rollover
Freed minimums accelerate the next target
extra += freed minimums
- When a debt clears, its minimum joins the pool
- The available extra grows each payoff
- This is what "snowballs" the plan
Repeats until every balance is zero.
- 1The fixture — note the smallest balance is not the highest APR: Store card $1,500 @ 12.99%; Card A $3,000 @ 26.99%; Card B $5,500 @ 22.99%; Personal loan $8,500 @ 14.99%. Minimums total $420/mo; with the $200 extra the plan funnels $620/mo. Because the smallest balance (Store card) is not the priciest debt (Card A), the two methods diverge.
- 2Avalanche (Card A → Card B → Personal loan → Store card): Debt-free in 40 months, total interest $6,065.29. First debt cleared at month 13 (Card A, the highest APR).
- 3Snowball (Store card → Card A → Card B → Personal loan): Debt-free in 41 months, total interest $6,538.02. First debt cleared at month 7 (Store card). So snowball costs about $473 more and one extra month — but delivers the first win six months sooner. That is the honest trade: behavioral momentum versus the mathematically lower bill.
If a minimum is below the monthly interest, the debt grows
The extra payment usually matters more than the method
It is tempting to agonise over snowball versus avalanche, but in the fixture that choice is worth about one month and $473. The amount you throw at the debt is a far bigger lever: bumping the extra from $200 to $300 a month cuts the payoff date faster than the avalanche edge does. That is why the calculator leads with the extra-payment amount, not the method toggle.
- 1Method choice — a small, fixed edge: Across the fixture, switching from snowball to avalanche saves ~$473 and one month. That edge is real but capped — it cannot grow beyond the interest-rate spread between your debts.
- 2Extra payment — an unbounded lever: Every extra dollar goes straight to principal on the target debt, cutting future interest and pulling the whole rollover chain forward. Raising the monthly extra compounds across every remaining month — so it routinely beats the method choice.
- 3The practical takeaway: Decide how much extra you can commit first; only then pick the method that keeps you motivated. A consistent larger extra payment with the "wrong" method beats a perfect method you abandon.
Two different wins — the early payoff and the lower bill
Most calculators report only the totals and declare avalanche "optimal." That is mathematically true but behaviorally incomplete. The two methods buy two different kinds of win, and seeing them side by side lets you weigh momentum against money honestly.
Snowball — the behavioral win
First debt cleared at month 7
The smallest debt is gone at month 7 — six months sooner than avalanche. That visible early payoff is what behavioral research links to higher completion rates.
Costs about $473 more interest over the plan.
Avalanche — the math win
Lower total interest
Total interest of $6,065.29versus snowball's $6,538.02 — the mathematically minimal bill, and one month faster overall.
First win arrives later (month 13).
Neither is universally right
Balance-transfer break-even — does the fee beat the interest saved?
Moving a high-APR balance to a 0% promotional card is the single most valuable action a high-rate cardholder can take — but only if the interest avoided during the promo exceeds the upfront transfer fee (typically 1–5% of the moved balance). The analyser computes that break-even.
- 1Fee vs interest avoided: The fee is a one-off percentage of the balance moved; the interest avoided is what you would have paid at your current APR over the promo months. If avoided interest exceeds the fee, the transfer is worth it.
- 2The balance you must clear before the promo ends: Any balance left when the 0% period ends is hit by the (often steep) go-to APR. The analyser shows the month you must clear it by to keep the full benefit.
- 3The simple-model caveat: Interest avoided is an upper bound — it assumes the full balance stays outstanding the whole promo period. As you pay down, interest accrues on a declining balance, so real savings are somewhat lower.
Cross-links
Frequently asked questions
Both methods pay the minimum on every debt and then funnel all spare cash at one target debt at a time, rolling the freed payment into the next debt as each clears. They differ only in the order: the avalanche targets the highest-APR debt first, which mathematically minimises total interest; the snowball targets the smallest balance first, which clears a debt sooner and builds motivational momentum. In the example fixture (4 debts, $18,500, $200 extra), avalanche is debt-free in 40 months with $6,065.29 interest, while snowball takes 41 months with $6,538.02 interest — but snowball clears its first debt at month 7 versus month 13 for avalanche.
Avalanche always saves at least as much interest, but the gap is usually small. In the example fixture it is only about $473 and one month — avalanche 40 months / $6,065.29, snowball 41 months / $6,538.02. For that ~$473, snowball clears its first debt at month 7 instead of month 13 — an early win research links to higher completion rates. Pick the one you will stick to.
The size of the extra payment usually moves your payoff date far more than the choice between snowball and avalanche. In the example fixture, switching method changes the result by about one month and $473; bumping the extra payment from $200 to $300 a month cuts the payoff date faster than that avalanche edge. So the most important decision is how much extra you can commit each month — that is why the calculator leads with the extra-payment amount, not the method toggle. Even small extra amounts compound into large interest savings over the life of the plan.
Each month the calculator charges interest on every debt (balance × APR ÷ 12), pays the minimum on each, and applies all spare cash — your extra payment plus the minimums freed from any cleared debts — to the single target debt set by your chosen method. When a debt hits zero, its full payment rolls into the next target. The payoff date is the month every balance reaches zero. The example fixture is debt-free in 40 months (avalanche) or 41 months (snowball) from a $620/month total commitment ($420 minimums + $200 extra).
It is worth it when the interest you avoid during the promotional 0% period exceeds the upfront transfer fee (typically 1–5% of the moved balance). The calculator computes this break-even: fee versus interest avoided, plus the balance you must clear before the promo ends to escape the often-steep go-to APR. Treat the interest-avoided figure as an upper bound — it assumes the full balance stays outstanding the whole promo period, whereas in reality interest accrues on a declining balance as you pay it down, so real savings are somewhat lower. A balance transfer is most powerful for high-APR card debt you can realistically clear within the promo window.
Method, assumptions & references
Methodology: each month interest = balance × APR ÷ 12; pay minimums on all debts; apply the global extra plus freed minimums to the #1 target (avalanche = highest APR, snowball = smallest balance); when a debt clears, its minimum joins the pool; repeat until all balances are zero. Interest saved is measured against a minimums-only baseline. Golden fixture (4 debts, $18,500, $200 extra): avalanche 40 months / $6,065.29 (first cleared month 13), snowball 41 months / $6,538.02 (first cleared month 7) — a ~$473 / ~1 month gap, stated honestly. Balance-transfer interest avoided is an upper bound (full balance assumed outstanding the whole promo). Currency-agnostic; APRs/balances are user inputs. Behavioral fit matters; not financial advice; APRs and terms vary.
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed 21 June 2026. Figures follow the methods and sources set out in our editorial standards.
The payoff schedule, interest totals, and balance-transfer break-even are computed from the APRs, balances, and extra payment you enter. Snowball costs slightly more interest but clears the first debt sooner — behavioral fit matters, and the right method is the one you will finish. This is general information, not financial advice; APRs, fees, and promotional terms vary by lender.
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