Debt Avalanche Calculator
✦ Finance & MoneyUse this debt avalanche calculator to pay off your highest-interest debt first, see how much interest you save versus the snowball method, and find your debt-free date.
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- ✓ Formula and sources shown
The formula
Debt avalanche payment allocation
P_{\text{target}} = M_{\text{target}} + \text{Extra} + \sum_{j \in \text{paid off}} M_j, \qquad \text{target} = \arg\max_i \text{APR}_iEach month, interest on every open debt is its balance × APR ÷ 12, rounded to the cent. You pay every minimum, then send all remaining money (extra, any one-time lump sum, and the minimums freed by cleared debts) to the open debt with the highest APR. Ties go to the smaller balance.
Calculating it by hand
- List every non-mortgage debt with its current balance, APR and required minimum payment.
- Add up the minimums and decide how much extra you can pay each month; that total is your fixed monthly budget.
- Rank the debts by APR, highest first. If two share a rate, put the smaller balance first.
- Pay every minimum, then send all the extra money to the top-ranked debt until its balance is zero.
- Roll that debt's full payment onto the next-highest APR and repeat until every balance is zero.
- Compare the interest and debt-free month with the snowball order to see what the ordering is worth for your numbers.
Worked examples
A 29% card behind a 6% loan: where the avalanche saves the most
Debts: Store card $1,500 at 9% (minimum $45), Auto loan $4,000 at 6% (minimum $120), Big card $9,000 at 29% (minimum $270). Minimums total $435; with $200 extra the monthly budget is $635.Month 1 interest: $1,500 × 9% ÷ 12 = $11.25, $4,000 × 6% ÷ 12 = $20.00, $9,000 × 29% ÷ 12 = $217.50. Total $248.75, so $386.25 of the $635 reduces principal.Avalanche order: Big card (29%) → Store card (9%) → Auto loan (6%). Big card is cleared in month 27, Store card in month 28 and Auto loan in month 29.Snowball order for comparison: Store card in month 7, Auto loan in month 16, Big card in month 31, with $5,164.99 of interest.
Avalanche: debt-free in 29 months with $3,803.65 total interest ($18,303.65 repaid). Snowball: 31 months and $5,164.99. Interest saved versus snowball: $1,361.34.
The same debts with a $1,000 one-time payment in month 1
Same three debts and $200 extra a month, plus a $1,000 lump sum applied in month 1.The avalanche sends the lump sum to the Big card (29%): it is cleared in month 23, Store card in month 24 and Auto loan in month 27.The snowball sends it to the Store card instead: Store card in month 3, Auto loan in month 13, Big card in month 29, with $4,602.52 of interest.
Avalanche: debt-free in 27 months with $3,011.69 total interest. Interest saved versus snowball: $1,590.83 and 2 months.
Three cards with similar rates: where the gap is trivial
Debts: Card A $3,000 at 19.5% (minimum $90), Card B $3,400 at 19% (minimum $95), Card C $3,200 at 18.5% (minimum $92). Minimums total $277; with $150 extra the budget is $427.Avalanche order: Card A → Card B → Card C. Card A is cleared in month 15, Card B in month 23 and Card C in month 28.Snowball order: Card A ($3,000) → Card C ($3,200) → Card B ($3,400). Card A is cleared in month 15, Card C in month 23 and Card B in month 28.Total interest: $2,337.81 under the avalanche, $2,344.56 under the snowball.
Both finish in 28 months. The avalanche saves $6.75 in interest because the three rates sit within one percentage point.
Methodology
How the debt avalanche works
The avalanche changes only the order, not the budget: every extra dollar goes to the highest-APR debt first. The saving depends on how far apart your rates are and how large the high-rate balance is, so it can be tiny or large.
Read sources and limitsWhat is the debt avalanche method?
The debt avalanche method is a way to pay off several debts in order of interest rate, highest APR first. You pay the required minimum on every account, then send all of your extra money to the debt with the highest APR.
When that balance reaches zero, you add its whole payment to the debt with the next-highest rate, and so on until every balance is gone. Balances do not decide the order; only rates do. Some sources call this approach debt stacking.
Your total monthly budget never changes. It is the sum of your minimums plus whatever extra you add, and as each debt clears, its minimum is freed and rolled onto the next target. The snowball method works the same way; the two differ only in which debt is next in line. If two debts share the same APR, this calculator pays the smaller balance first.
How much interest does the avalanche save versus the snowball?
It depends on your numbers, so this page shows the gap for your own debts. With the sample debts loaded here (a $1,500 store card at 9%, a $4,000 auto loan at 6% and a $9,000 card at 29%) and $200 extra a month, the avalanche costs $3,803.65 in interest and clears everything in 29 months.
The snowball, which attacks the $1,500 balance first, costs $5,164.99 and takes 31 months: a difference of $1,361.34 and 2 months. Paying only the minimums would take 69 months and cost $10,136.34.
The saving comes from the 29% card. Under the avalanche it is cleared in month 27 and collects $3,229.18 of interest; under the snowball it stays open until month 31 and collects $4,917.54. Adding a $1,000 one-time payment in month 1 widens the gap to $1,590.83, with the avalanche finishing in 27 months against 29.
When is the difference between avalanche and snowball small?
The gap shrinks when your rates are close together. Take three cards at 19.5%, 19% and 18.5% with balances of $3,000, $3,400 and $3,200, minimums of $90, $95 and $92, and $150 extra. The avalanche costs $2,337.81 in interest and the snowball $2,344.56, a difference of $6.75, and both finish in month 28.
At that point the interest gap is small enough that other considerations, such as how soon the first account closes, may weigh more in your own decision.
The gap is large when a high-rate balance is also big, as in the first example: a 29% card sitting behind a 6% loan. The first account closes later under the avalanche (month 27, against month 7 for the store card under the snowball), so the benefit builds slowly before it shows. This calculator shows both timelines and both orders side by side so you can see the trade-off for your own debts. Experiments find that people with several debts tend to clear the smallest balances first even when that costs more interest (Amar et al., 2011), so the avalanche order usually takes a deliberate choice.
What does this avalanche calculator not model?
Interest is calculated as APR divided by 12 on each month's opening balance, rounded to the cent, with payments made at month end. Real cards often compound daily and lower the minimum as the balance falls; this calculator keeps each minimum fixed at the amount you enter, so use the figures from your statements and expect small differences.
It does not model promotional rates that expire, balance-transfer fees, late fees, variable-rate changes or new charges.
The result is an estimate from the figures you enter, not financial, credit or legal advice, and it does not know your card agreement, your lender's terms or your credit file. If a card has a promotional rate that will end, entering the APR that applies afterwards shows the order that matters once the promotion is over.
Debt Avalanche questions
What is the debt avalanche method?
The debt avalanche method pays off several debts in order of interest rate, highest APR first. You pay the minimum on every account and put all extra money toward the debt with the highest rate. When it is cleared, you add its whole payment to the next-highest rate. Your total monthly payment stays the same throughout; only the order of payoff changes.
How much interest does the debt avalanche save compared with the snowball?
$1,361.34 with the sample debts on this page: $3,803.65 under the avalanche against $5,164.99 under the snowball, with $200 extra a month. Your figure depends on how far apart your rates are and how big the high-rate balance is. With three cards at 19.5%, 19% and 18.5% the difference falls to $6.75.
Is the debt avalanche always faster than the snowball?
No. With the sample debts it finishes 2 months sooner (29 months against 31), but with three similar-rate cards both methods finish in month 28. The avalanche is built to reduce interest, and months saved follow only when the interest saving is large enough to bring the last payment forward. Enter your own debts to see both timelines.
What if two debts have the same interest rate?
This calculator pays the smaller balance first when two debts share an APR. Two debts at the same rate charge the same interest per dollar owed, so clearing the smaller one first closes an account sooner at no extra cost in rate terms. If all of your debts share one rate, the avalanche and snowball results are identical.
Where does my extra money go each month?
Every month the calculator pays each open debt its minimum, then sends everything left (your extra payment, any lump sum in month 1 and the minimums freed by debts already cleared) to the open debt with the highest APR. If the top debt needs less than that amount to finish, the leftover moves to the next-highest rate in the same month.
Is debt stacking the same as the debt avalanche?
In most sources, yes: debt stacking is another name for paying debts in order of interest rate, highest first, while rolling freed payments onto the next debt. Because the term is used loosely, check how a particular guide defines it. Here the rule is exact: highest APR first, minimums on everything else, smaller balance first on a tie.
How should I enter a 0% promotional card?
Enter the APR that applies today to see the order for now, or the APR that applies after the promotion to see the order once it ends. This calculator uses one fixed rate per debt and does not switch rates on a date, so for a promotion that expires partway through, run it both ways and compare the two plans.
Can I download or share my avalanche payoff schedule?
Yes. Under the chart, open the schedule bar to download the month-by-month plan as a CSV file, print it or copy a share link. The link stores your debts in the address itself, after the # sign, so it is never sent to a server. Nothing you type is saved anywhere else.
Source notes
Method, sources & limitations
Every figure on this page comes from the formula above applied to the values you enter. Nothing is estimated from market data, and no result is a forecast. These are the sources behind the method and any fixed figures it uses:
- Consumer Financial Protection Bureau (CFPB) — How can I reduce my debt?
- Federal Trade Commission (FTC) — Coping with Debt
- Amar, Ariely, Ayal, Cryder & Rick (2011), Winning the battle but losing the war: the psychology of debt management, Journal of Marketing Research 48(SPL), S38–S50
- Kettle, Trudel, Blanchard & Häubl (2016), Repayment concentration and consumer motivation to get out of debt, Journal of Consumer Research 43(3), 460–477
Educational information only. Results are estimates produced from the assumptions you enter, and are not financial, tax, legal or medical advice. Check anything that matters against a qualified professional and the cited sources.