Debt Avalanche Calculator
Find out how quickly you can eliminate debt by attacking the highest-interest balances first. Enter your debts, minimum payments, and any extra cash to see your payoff timeline using the avalanche method.
About this calculator
The debt avalanche method directs every extra dollar toward the debt with the highest interest rate while paying minimums on all others. Once the costliest debt is eliminated, you roll that freed-up payment onto the next highest-rate debt. This minimizes total interest paid over time compared to other strategies. The estimated payoff period is calculated using the formula: months = CEIL(−ln(1 − (totalDebt × (r/12)) / (minPayments + extra)) / ln(1 + r/12)), where r is the average annual interest rate expressed as a decimal. This logarithmic formula is derived from the standard loan amortization equation solved for the number of periods. The avalanche method is mathematically optimal for reducing interest costs, though it requires discipline when high-rate debts also carry large balances.
How to use
Suppose you have $12,000 in total debt at an average rate of 18% (r = 0.18), a highest rate of 24%, total minimum payments of $300/month, and you can put an extra $150/month toward debt. Plug in: months = CEIL(−ln(1 − (12000 × (0.18/12)) / (300 + 150)) / ln(1 + 0.18/12)). Calculate: monthly rate = 0.015; numerator inside ln = 1 − (180/450) = 1 − 0.4 = 0.6; ln(0.6) = −0.5108; ln(1.015) = 0.01489; months = CEIL(0.5108 / 0.01489) ≈ CEIL(34.3) = 35 months. You would be debt-free in about 35 months — nearly 3 years.
Frequently asked questions
How does the debt avalanche method save more money than the debt snowball method?
The avalanche method targets your highest-interest debt first, which directly reduces the rate at which interest accrues across your entire debt portfolio. Because high-interest balances compound aggressively, eliminating them early prevents a snowballing interest burden. Studies and simulations consistently show the avalanche method results in less total interest paid compared to the snowball method, though the difference varies by your specific interest rates and balances. The trade-off is psychological: you may not see a debt fully eliminated as quickly if your highest-rate debt is also your largest.
What extra payment amount makes a meaningful difference in debt avalanche payoff time?
Even a modest extra payment of $50–$100 per month can shave months or years off your payoff timeline, depending on your total balance and interest rates. The impact is non-linear — because interest compounds monthly, earlier extra payments reduce the principal that future interest is calculated on. For a $10,000 balance at 20% APR, adding $100/month extra can cut repayment time by over a year. Use this calculator to experiment with different extra payment amounts to find the sweet spot for your budget.
When should I use the debt avalanche method instead of the debt snowball method?
The avalanche method is best when you are motivated by minimizing total interest costs and your highest-rate debts are not necessarily your smallest balances. It suits people who can stay disciplined even if it takes longer to fully pay off the first debt. If your highest-rate debt is also among your smaller balances, the avalanche and snowball methods may produce nearly identical results. Choose the snowball method if you need quick psychological wins to stay motivated, but choose the avalanche method if saving the most money is your primary goal.