Debt Avalanche Calculator
Free debt avalanche calculator — the mathematical optimum for repaying multiple debts. Enter up to 5 debts with balance, APR, and minimum payment. Sorts by highest rate first to minimize total interest. Runs in your browser.
List your debts. The calculator sorts them highest APR first — the avalanche order — and simulates month by month: interest accrues on every balance, minimums are paid, and your monthly surplus goes entirely to the most expensive debt. When a debt hits zero, its minimum payment is freed up and rolled into the surplus for the next month.
Avalanche vs. snowball
The avalanche (this calculator) sorts debts highest APR first. The snowball sorts smallest balance first.
| Method | What it minimizes | Psychological effect |
|---|---|---|
| Avalanche | Total interest | Slow at first if big debts have high rates |
| Snowball | Number of open debts | Quick wins — small debts vanish fast |
Both methods work. The avalanche saves the most money — always. The snowball keeps you motivated. If the interest difference is small, pick the one you’ll actually follow through on. If someone’s charging you 29% on a $15,000 balance, you want the avalanche.
How the simulation works
Each month:
- Interest accrues on every remaining balance.
- Minimums are paid on every debt.
- The surplus goes entirely to the highest-rate active debt.
- When a debt reaches zero, its minimum payment is added to the surplus for the next month — the same cascading effect as the snowball, just targeted differently.
The calculator runs for up to 50 years (600 months). If any debt isn’t paid off by then, the plan is flagged incomplete.
Minimum payment trap
If a credit card’s minimum payment is less than the monthly interest (common with high-APR cards and 1% minimums), the balance grows even while you pay. The calculator warns you when this happens — you need a higher minimum or a bigger surplus to make progress.
Make it work
The most powerful input is the monthly surplus — the money you free up beyond minimums. Because the avalanche attacks your most expensive debt first, every extra dollar of surplus avoids the highest possible interest rate in your portfolio. This is where the avalanche’s math edge really compounds.
Worked examples
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Two credit cards (22% and 18%) plus a car loan (8%) with $200/month surplus — avalanche order
Avalanche plan (2 yrs, 5 mos): Credit card A: 6 mos | Credit card B: 1 yr, 6 mos | Car loan: 2 yrs, 5 mos. Total interest: $1,683.31.
Frequently asked questions
What is the debt avalanche method?
The debt avalanche method pays off debts **highest interest rate first**. You make the minimum payment on all debts, then direct every extra dollar at the debt with the highest APR. When that one is gone, you move to the next-highest rate — and so on. It's the mathematical optimum: you minimise total interest paid. The tradeoff is psychological — if your highest-rate debt also has the biggest balance, you might go months without seeing a debt fully disappear, unlike the **snowball** method.
Debt avalanche vs. debt snowball — which should I use?
**Avalanche** saves the most money — always. If your highest-rate debt is also small, it's a no-brainer: you get the math *and* the motivation. But if your 28% credit card has a $15,000 balance while a $500 store card sits at 0%, the avalanche has you grinding on the big one for months while the snowball would have knocked out two small debts already. Studies show snowballers have higher completion rates because of those early wins. The best method is whichever one you'll *stick with*. Try both calculators and see the interest difference — it might be small enough that the psychological edge of snowball is worth it.
How much more interest does the snowball cost?
It depends entirely on your debt mix. If all your debts have similar APRs, the difference is negligible. If you have a crushing 29% card alongside a 3% car loan, the avalanche saves real money — potentially hundreds or thousands. Use this calculator to get your avalanche numbers, then compare with a snowball calculator to see the exact difference for your situation.
What's 'monthly surplus'?
The extra money you can commit *above* all minimum payments each month. Every dollar of surplus goes straight to the highest-rate debt. A bigger surplus shrinks the total interest dramatically because it attacks the most expensive debt first. Even $50/month makes a material difference.
Does minimum payment size affect avalanche order?
No — the avalanche sorts purely by **interest rate**, not by balance or minimum payment. A $500 debt at 29% comes before a $50,000 debt at 28%. That's the mathematical optimum: every dollar you pay early avoids the highest cost of borrowing possible.