Debt Snowball Calculator
Free debt snowball calculator — plan your smallest-balance-first repayment. Enter up to 5 debts with balance, APR, and minimum payment to see your payoff plan and total interest. Runs in your browser.
List your debts — credit cards, personal loans, car loans, anything with a balance and an interest rate. The calculator sorts them smallest balance first (the snowball order) and simulates month by month: interest accrues, minimums are paid, and your monthly surplus goes entirely to the smallest active debt. When a debt hits zero, its minimum payment permanently joins the surplus, accelerating the next one.
Debt snowball vs. debt avalanche
The snowball (this calculator) sorts debts smallest balance first. The avalanche sorts debts highest APR first. Avalanche saves more in total interest — it’s the mathematical optimum. Snowball gives you quick wins by killing small debts early, which keeps you motivated. Studies suggest people on the snowball are more likely to finish paying off all debts. Both methods work; pick the one you’ll stick with.
How the simulation works
Each month:
- Interest accrues on every remaining balance.
- Minimums are paid on every debt.
- The surplus goes entirely to the smallest active debt.
- When a debt reaches zero, its minimum payment is added to the surplus for the next month — the “snowball” effect.
The calculator runs the simulation for up to 50 years (600 months). If a debt isn’t fully paid by then, the plan is labeled 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 every month even while you’re paying. This calculator detects that and shows a warning — you need a higher minimum or a bigger surplus to make progress.
Make it work
The most important input is your monthly surplus — the extra money you can commit above all minimums. Even $50/month makes a material difference over time. Cutting a subscription or packing lunch once a week can fund a surplus that shaves years off your payoff plan.
Worked examples
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Two credit cards ($1,200 at 22% and $3,500 at 18%) plus a car loan ($8,000 at 8%) with $200/month surplus
Payoff 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 snowball method?
The debt snowball method pays off debts **smallest balance first**, regardless of interest rate. You make the minimum payment on all debts, then throw every extra dollar at the smallest one. When the smallest is gone, you take its old minimum payment (the 'snowball') and add it to the payment on the next-smallest debt — and so on. It's mathematically not the cheapest method (the **avalanche** — highest APR first — saves more interest), but the quick psychological wins from killing small debts keep people motivated.
Debt snowball vs. debt avalanche — which is better?
**Avalanche** (highest interest rate first) minimizes total interest paid — it's the mathematical optimum. **Snowball** (smallest balance first) maximizes motivation by giving you early 'wins' — you see debts disappear faster. Studies show people who use the snowball are more likely to stick with the plan and actually *finish* paying off all debts. The best method is the one you'll follow through on. Use this calculator to see your snowball plan; compare with an avalanche calculator to see how much extra interest you'd save.
How do minimum payments work?
Minimum payments are set by your lender — typically 1–3% of the balance for credit cards, or the full scheduled payment for installment loans. If a minimum payment is less than the monthly interest, the balance grows even while you're paying — that's **negative amortization**. This calculator will warn you if that's the case, because the snowball can't work with a growing balance.
What's 'monthly surplus'?
It's the extra money you can commit *above* all your minimum payments each month. Could be $50 from cutting a subscription, $200 from side work, or $500 from a budget overhaul. The bigger the surplus, the faster the snowball rolls. Set it to $0 to see what happens with minimums only (warning: it might take decades).
Does this calculator account for fees?
No — it works with balances, APRs, and minimum payments only. Annual fees, late fees, or balance-transfer fees aren't modeled. Use the APR to capture the all-in cost as closely as possible; for credit cards, the purchase APR is usually the right number.