Debt Payoff Calculator: Avalanche vs Snowball
Enter your debts and an extra monthly payment to see how long payoff takes and how much interest you pay with the avalanche (highest APR first) and snowball (smallest balance first) methods.
Both methods pay minimums on everything and throw extra money at one debt at a time. Avalanche targets the highest APR and saves the most interest; snowball targets the smallest balance and gives faster wins. This calculator runs both on your actual debts.
How the simulation runs
Each month every debt accrues interest at APR/12 and receives its minimum payment. Your extra amount, plus any minimum freed up by a paid-off debt, goes to the target debt: the highest APR under avalanche, the smallest balance under snowball. When the target is cleared, the next one takes over. Minimums are held constant rather than shrinking with the balance, which is how to pay debt off fastest.
Which to choose
Avalanche is mathematically optimal. Snowball usually costs a little more interest but clears the first account sooner, and research on debt repayment consistently finds that early wins improve follow-through. If the difference above is small, pick snowball; if it is large, pick avalanche and automate it.