Debt Snowball Calculator
See how long a fixed payment takes to clear a debt.
Results update as you type.
How it works
The months-to-payoff figure shown here is how long a fixed monthly payment takes to eliminate a debt, and the total interest is the extra you pay on top of the balance to get there. It matters because the debt snowball method — attacking one balance with a steady, committed payment until it is gone — depends on knowing your finish line, and seeing the timeline and interest cost turns a daunting balance into a concrete plan with an end date. This debt snowball calculator converts the annual rate to a monthly rate, charges interest on the shrinking balance each month, and solves for the number of payments that drive the balance to zero, then reports the interest accumulated along the way. The logarithmic formula is needed because the balance falls by a different amount every month — early payments cover more interest, later ones more principal — so the payoff curve is not a straight line. Borrowers use a debt snowball calculator to estimate how long a single debt will take, to see how raising the payment shortens the timeline and cuts interest, and to stay motivated as the balance drops. A crucial guardrail appears here: if the payment does not exceed the monthly interest, the balance never shrinks and the debt is never repaid, so the tool returns no result to signal that the payment must rise.
n = −ln(1 − debt × r ÷ payment) ÷ ln(1 + r), r = APR ÷ 1200
The monthly rate r is the APR divided by 1200. Each month interest of debt × r is added and the payment reduces what remains, so the balance follows a declining curve rather than falling in equal steps. Rearranging that curve to solve for the number of payments gives n = −ln(1 − debt × r ÷ payment) ÷ ln(1 + r). If the payment is less than or equal to debt × r, the value inside the logarithm is zero or negative, no finite payoff exists, and the tool shows no result — a warning that the payment must exceed the monthly interest to make progress.
Source:Consumer Financial Protection Bureau (CFPB)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter total debt, monthly payment and interest rate (apr).
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Months to payoff updates instantly as you type — no button to press.
Frequently asked questions
What is the debt snowball method?
The debt snowball is a payoff strategy where you list your debts smallest to largest, make minimum payments on all of them, and throw every extra dollar at the smallest balance until it is gone. You then roll that freed-up payment onto the next debt, building momentum like a snowball. Its strength is psychological: clearing small balances quickly delivers early wins that keep you motivated, even though it is not always the cheapest order mathematically.
How is the snowball different from the avalanche method?
The snowball orders debts by balance, smallest first, to maximize motivation from quick wins. The debt avalanche orders them by interest rate, highest first, to minimize total interest paid. The avalanche is usually cheaper overall, but the snowball's early victories help many people stick with the plan. This tool computes the payoff time and interest for a single debt at a fixed payment, which applies to whichever ordering strategy you choose to follow.
Why does the payment have to exceed the monthly interest?
Each month, interest is charged on the outstanding balance. If your payment is only equal to or less than that interest, the entire payment is consumed by interest and the principal never falls, so the debt lasts forever or even grows. For the balance to shrink, the payment must cover the month's interest and leave something over to reduce principal, which is why the tool returns no result when the payment is too small.
How much interest will I pay in total?
The total interest is the sum of all your payments minus the original balance — the extra you hand the lender for the privilege of borrowing. It depends heavily on the interest rate and how fast you pay: a higher rate or a smaller payment stretches the timeline and multiplies the interest. Raising your monthly payment shortens the payoff and can cut total interest sharply, since the balance that accrues interest shrinks faster.
How can I pay off my debt faster?
Increase the monthly payment, since every extra dollar goes straight to principal and reduces the interest charged the following month, compounding the benefit. You can also lower the rate through a balance transfer or consolidation loan, freeing more of each payment for principal. Even modest increases in the payment can shave months off the timeline. Try raising the payment in this tool to see how quickly both the months and the total interest drop.