When you're juggling more than one debt, the order you pay them off in changes both how fast you're debt-free and how much interest you pay along the way. This calculator simulates two common strategies — snowball and avalanche — so you can see the real difference in numbers rather than guessing.
How to Use This Debt Payoff Calculator
Add each debt you're paying down, with its balance, interest rate, and minimum payment. Choose a strategy — avalanche targets the highest interest rate first, snowball targets the smallest balance first — and enter how much extra you can put toward debt each month beyond the minimums. The calculator simulates every debt month by month under your chosen strategy and shows the comparison against the alternative.
How the Snowball Effect Works
Every dollar of minimum payment keeps flowing even after a debt is paid off — it doesn't disappear, it rolls into the extra payment attacking whichever debt is next in line. That rollover is what makes both strategies accelerate over time rather than progressing at a constant pace, and it's the main reason either one beats paying only minimums on every debt indefinitely.
Snowball vs. Avalanche
Avalanche orders debts by interest rate, highest first, which is mathematically optimal — it minimizes the total interest paid across all your debts. Snowball orders debts by balance, smallest first, which usually costs a bit more in interest but produces a fully paid-off debt sooner. Many people find that early win easier to stay motivated by, even though it's not the lowest-cost path in pure dollar terms.
Example Calculation
Three debts — a $4,500 credit card at 22%, a $1,200 store card at 27%, and a $12,000 car loan at 6.5% — with a combined $425 in minimum payments and $200 extra a month, would have avalanche attack the 27% store card first (despite its smaller balance being incidental), while snowball would also start there since it happens to be the smallest balance too. The two strategies would diverge once the store card is cleared and the next target differs.
What Determines How Much a Strategy Saves
- Spread between interest rates — when your highest-rate debt is far above the others, avalanche's savings over snowball are largest.
- Extra payment size — a larger extra payment shortens payoff time for both strategies and shrinks the dollar gap between them.
- Number of debts — more debts mean more rollover events, amplifying the snowball effect for whichever strategy you choose.