Compare the snowball and avalanche methods — see your debt-free date and interest saved side by side.
Two people with identical debts can end up paying thousands of dollars more or less in total interest depending solely on which payoff strategy they follow. The debt snowball and debt avalanche methods both work — but they optimize for different things, and understanding the difference helps you pick the one you'll actually stick with.
Snowball targets the smallest balance first, regardless of interest rate. You pay the minimum on all other debts and put every extra dollar toward the lowest-balance account. When it's paid off, you roll that freed minimum (plus your extra) to the next smallest. The idea is behavioral: eliminating a debt entirely — even a small one — delivers a psychological win that keeps people motivated through a long payoff journey.
Research on behavior change backs this up. People who see visible progress (a debt gone from their list) are more likely to keep making sacrifices than people grinding toward a distant, abstract "lower total interest" goal. Snowball's payoff order for the example debts above is Credit Card C ($1,000) → Credit Card A ($2,000) → Credit Card B ($6,000).
Avalanche targets the highest APR first. Because high-rate debt is the most expensive per dollar per month, eliminating it first minimizes the total interest you pay over the life of your debt. The math is unambiguous: avalanche can never pay more interest than snowball for the same set of debts and payment amounts. With the example debts, the avalanche order is Credit Card B (28%) → Credit Card C (25%) → Credit Card A (22%).
The trade-off: Credit Card B has a $6,000 balance. It may take many months before you see it disappear, and for some people that wait erodes motivation. If you're the kind of person who can stay disciplined watching a number fall without crossing zero, avalanche is strictly better on cost. If you need to see a debt fully paid off to stay on track, snowball may save you more in practice even if it costs more in theory.
This calculator runs a month-by-month simulation. Each month: (1) interest accrues on every remaining balance — computed as balance × APR ÷ 12; (2) the minimum payment is applied to every non-target debt; (3) the target debt receives the minimum plus your extra payment plus any minimums freed by previously paid-off debts. The simulation advances until all balances reach zero or 600 months have elapsed.
The "credit card payoff calculator" problem is a subset of this tool. Any revolving or fixed-rate debt — credit cards, personal loans, car loans, student loans — can be entered here. The math is identical; only the APR and minimum differ per account type.
Starting with Credit Card A ($2,000 @ 22%, min $50), Credit Card B ($6,000 @ 28%, min $120), and Credit Card C ($1,000 @ 25%, min $25), with $200 extra per month:
The snowball method focuses on Credit Card C first. By the time C is gone, its freed $25 minimum joins the extra payment pot, which then pummels Credit Card A, and so on. The avalanche method goes straight for Credit Card B — the highest rate — even though it's the largest balance. The comparison table above shows exactly how many months each strategy takes and how many dollars each costs in interest. Avalanche will show lower total interest; how much lower depends on the rate gap between your debts.
If any debt's minimum payment is smaller than its monthly interest charge, the balance grows despite your payments. This calculator detects that condition and shows a warning. The fix is straightforward: increase the payment above the monthly interest. For a $10,000 balance at 36% APR, the monthly interest alone is $300 — a $25 minimum accomplishes nothing. Always check that every minimum is at least slightly above the monthly interest figure before committing to a payoff plan.