About the Debt Snowball Calculator
With the debt snowball method, you keep making minimum payments on every debt and put any extra money toward the debt with the smallest balance. When that debt is gone, its payment "snowballs" into the next-smallest one.
Enter your debts, and the calculator estimates your payoff time, debt-free date, total interest, and the order debts are paid off. It also runs the avalanche method with the same payments so you can compare the numbers.
How It Works
Each month, interest is added to every balance at its APR ÷ 12. Every debt receives its minimum payment, and the rest of your monthly budget goes to the debt with the smallest starting balance (ties go to the higher APR).
When a debt is paid off, your total monthly budget stays the same, so the freed-up minimum is applied to the next debt in line. This continues until every balance is $0.
Formula
Example
Three debts — Credit card A: $3,000 at 24.99% ($90 minimum), Car loan: $12,000 at 6.5% ($280), Credit card B: $800 at 19.99% ($35) — plus $200 extra per month.
Inputs
- Total balance
- $15,800
- Minimums
- $405/mo
- Extra payment
- $200/mo
Results
- Snowball payoff time
- 2 years, 6 months
- Snowball total interest
- $1,776.69
- Avalanche (same payments)
- $1,741.49
- Saved vs. minimums only
- $2,303.64
Both methods use the same monthly budget; only the order of focus payments changes. Interest saved is compared with paying only each debt's minimum without rolling payments over.
Assumptions & Limitations
- Fixed APRs and minimum payments; real minimum payments on credit cards usually fall as balances fall.
- No new charges on any account during payoff.
- Interest is charged monthly at APR ÷ 12; lenders may use daily balances.
- Payments rolled over: when a debt is paid off, its minimum is added to the next focus debt.
- Not included: fees, promotional 0% periods ending, balance transfers, and consolidation loans.
Understanding Your Results
- Estimated Payoff Time: How long until every debt reaches $0 with this method.
- Interest Saved: Difference in total interest compared with paying only each minimum (no rollover, no extra).
- Method comparison: Snowball and avalanche results side by side with the same payments, showing numerical differences only.