Debt Snowball vs Avalanche Calculator

How the two strategies work

Both the debt snowball and the debt avalanche start the same way: you pay the minimum payment on every debt, then put every spare dollar on a single target debt. The only difference is how the target is chosen. The snowball attacks the smallest balance first. Clearing a debt quickly gives a visible win and frees its minimum payment for the next one. The avalanche attacks the highest interest rate (APR) first, so the most expensive debt shrinks fastest and less interest piles up overall.

The math behind the simulation

Each month the calculator adds interest to every open balance: interest = balance × APR ÷ 12 ÷ 100. It then pays each debt's minimum, and sends what remains of your fixed monthly budget to the target debt. The budget is sum of all minimums + extra payment, and it does not shrink when a debt is cleared — the freed-up minimum "rolls over" to the next debt. The loop repeats until every balance reaches zero. Total interest is the sum of monthly interest, and the debt-free date is today plus the number of months needed. If the budget is not larger than the monthly interest, balances never fall and the tool tells you the plan does not finish within 50 years.

Choosing a method and staying on track

The avalanche is optimal on cost, but the gap depends on how different your rates are and how much extra you pay. With similar APRs the two methods can finish almost together, so the snowball's motivation boost may be worth a few dollars. Try different extra payments to see how sharply the payoff date moves: even a small increase often saves months. Always keep paying at least the minimum on every account to avoid late fees and credit damage, and avoid adding new charges while you pay down. This tool is an educational estimate that uses simple monthly compounding; lenders may compute interest daily and apply fees. It is not financial advice — check real figures with your lenders before making decisions.