Debt Avalanche Calculator

The debt avalanche method is a debt repayment strategy where you focus extra payments on the debt with the highest interest rate first, while making minimum payments on all other debts. Once the highest-rate debt is paid off, you redirect those payments to the next highest-rate debt, and so on.

Why avalanche is mathematically optimal: By targeting the highest interest rate first, you minimize the total amount of interest paid over the life of all your debts. This makes it the most cost-efficient debt repayment strategy available.

How the calculation works:

1. List all debts with their balances, interest rates, and minimum payments
2. Allocate any extra monthly payment to the highest-rate debt
3. When that debt is paid off, add its minimum payment plus extra to the next highest-rate debt
4. Continue until all debts are cleared

The interest saved compared with paying the bare minimum is larger than most people expect. A $10,000 credit card balance at 22% APR paid at $200 a month takes 137 months, that is 11 years 5 months, and costs $17,356 in interest. You repay nearly three times what you borrowed. Push the payment to $300 and it clears in 52 months for $5,596, saving $11,760 and seven years.

An extra $100 a month is $5,200 of your own money over those 52 months. It buys back $11,760. That is the whole argument in one line, and it is why the order you attack debts in matters less than the amount you throw at them.

Avalanche vs. Snowball method: The snowball method (targeting the smallest balance first) provides psychological wins by eliminating debts faster. The avalanche method saves more money overall. This calculator runs both and shows you the difference for your own numbers, which is usually smaller than people expect: on two debts a few hundred dollars is typical, and it only becomes worth arguing about when the rate gap is wide and the high-rate debt is also the larger one.

If the snowball is what actually keeps you paying, the snowball is the better method. A plan you abandon in month four saves nothing at all.

Key factors in the calculation:

• Total monthly budget: the more you can put above the minimums, the faster you are done. This matters more than the ordering.
• Interest rates: a wide gap between the two rates is what makes avalanche worth the discipline. A narrow gap makes the choice almost irrelevant.
• Balance sizes: avalanche pulls furthest ahead when the high-rate debt is also the large one, because that is exactly the case snowball leaves for last.

Important tips for success: Stop accumulating new debt while paying off existing balances. Build a small emergency fund first to avoid using credit cards for unexpected expenses. Consider balance transfer offers or debt consolidation if available at lower rates. Even small extra payments make a significant difference over time.

This calculator models two debts for clarity, and assumes the debt you are not targeting gets a fixed minimum of 2% of its starting balance or $25, whichever is larger. The same principle extends to any number of debts: everything spare goes at the highest rate, minimums everywhere else, and each cleared debt hands its payment to the next one down the list.