Debt Snowball Calculator

Background.

Which debt should you pay off first? The snowball's answer is the smallest balance, whatever its interest rate. You keep paying the minimum on everything, put every spare dollar on the smallest debt until it is gone, then add that debt's old minimum to your spare dollars and aim the bigger payment at the next-smallest. Each debt you clear makes the next payment larger, which is where the name comes from.

The case for doing it this way is behavioral rather than mathematical. Clearing a whole account in a few months is progress you can see, and every closed balance means one fewer due date and one fewer minimum to keep track of. The price of that motivation is interest. Paying the highest-rate debt first, the avalanche method, never costs more and usually costs less. With this calculator's starting figures, a $5,000 card at 18.99% and a $3,000 card at 15.99% with $200 a month on top of the minimums, the snowball pays $1,409.16 in interest and the avalanche $1,330.69, both finishing in 21 months. Whether $78.47 is a fair price for clearing the first card sooner is your call, and when the smallest debt also carries the highest rate the two methods are the same plan.

Enter up to three debts with their balances, annual rates and minimum payments, plus the extra amount you can commit every month. The calculator works through the plan a month at a time and reports how long until the last balance is gone, how much interest you pay on the way, and the order the debts are cleared.

The plan assumes it is followed exactly: no new charges, no missed payments, no rate changes and the same total payment every month. Most real repayment plans meet a setback or two, so the month count is what the plan achieves if it holds. If even that timeline is longer than you can manage, the Federal Trade Commission's guide to getting out of debt covers talking to creditors early, nonprofit credit counseling, and the risks of debt-settlement companies that charge before they have settled anything.

What is debt snowball calculator?

The debt snowball is a repayment order. Debts are ranked by balance, smallest first, and the ranking ignores interest rates entirely. Every debt gets its minimum payment each month; all the money beyond the minimums goes to the debt at the top of the list. When that debt is cleared, its minimum payment is not pocketed but added to the extra, so the next debt receives its own minimum plus everything that used to go to the first one. One consequence is easy to miss: the total you pay each month never rises. It stays at the sum of all the minimums plus your extra, and what changes is how much of it lands on a single debt. The snowball works best on debts of very different sizes, such as a small store card, a mid-sized credit card and a personal loan, where the first win comes quickly.

How to use this calculator.

1. 01Take each balance, annual percentage rate and minimum payment from your latest statements. Use the rate you are being charged now, not a promotional rate that is about to end.
2. 02Enter up to three debts. Names are optional and only label the payoff order. Debt 1 needs a balance and a minimum payment above zero; leave the balance of an unused Debt 2 or Debt 3 at 0 and it is left out.
3. 03Enter the extra monthly payment: the amount you can reliably add on top of all the minimums every month. With 0, the snowball still rolls each cleared debt's minimum into the next one.
4. 04If you have more than three debts, enter the three smallest and keep paying the minimums on the others outside the plan; the result then covers those three.
5. 05Read the months to debt-free, the total interest and the payoff order. To see what the snowball's motivation costs, enter the same figures in the debt avalanche calculator, which pays the highest rate first.

The formula.

There is no single equation for a snowball, because each month depends on which debts are still open, so the calculator simulates the plan one month at a time.

First the debts are ranked by starting balance, smallest first; two debts with exactly the same balance are ranked higher-rate first. The ranking is fixed for the rest of the plan. Then, each month: every open debt is charged interest of balance × APR ÷ 1,200, which is the annual rate divided by twelve months and by 100 to turn a percentage into a fraction. Each open debt then receives its minimum payment, or the whole remaining balance if that is smaller. Finally the snowball amount, your extra payment plus the minimums of every debt already cleared, goes to the highest-ranked open debt. If it is more than that debt needs, the debt is cleared and the remainder moves on to the next debt in the same month. Any debt that reaches zero in a month, whether its own minimum or the snowball cleared it, is closed that month and adds its minimum to the snowball from the following month.

Total interest is the sum of every monthly interest charge, shown to the cent. The month count is the number of months simulated until every balance is zero, the last one usually a part payment.

The model simplifies in a few places. Card issuers usually charge a daily rate on the average daily balance, so a month's interest depends on its length and on when you pay; on a $5,000 balance at 18.99% the monthly-rate method charges $79.13, while a daily rate gives about $78.04 over a 30-day cycle and $80.64 over 31 days. Minimum payments are held fixed, fees and penalty rates are left out, and the calculator refuses to run past 100 years (1,200 months), reporting an error if the payments never get ahead of the interest.

A worked example.

Frequently asked questions.

References& sources.

1. [1]FTC (2025). "How To Get Out of Debt."
2. [2]CFPB (2024). "How does paying down a mortgage work?"
3. [3]CFPB (2023). "How should I use lender credits and points (also called discount points)?"
4. [4]CFPB (2024). "What is a credit report?"
5. [5]myFICO (2024). "What's in my FICO Scores?"