Snowball or avalanche?
Both methods pay the minimum on every debt and throw every spare dollar at one target. When that debt is gone, its payment “rolls over” onto the next. They differ only in the order:
- Debt avalanche: highest interest rate first. Mathematically it always costs the least interest and is usually fastest.
- Debt snowball: smallest balance first. You knock out whole debts sooner, and those early wins help many people stick with the plan.
- The gap is often small. If your smallest debts also carry high rates, both orders are the same. If not, this calculator shows exactly what the snowball’s motivation costs.
Not sure what you can afford? Leave the extra payment blank and enter a goal (say, 24 months). The calculator finds the smallest extra payment that gets you there with the avalanche plan.
How it’s calculated
Each month, interest accrues on each balance at APR ÷ 12, every minimum gets paid, and the rest of your budget goes to the target debt. If your total payment can’t even cover the monthly interest, you’ll see a warning instead of an endless timeline. The extra payment for a goal is found by bisection on the payment amount. See the methodology.