WealthDebt Payoff Calculator — Snowball vs Avalanche
Debt payoff calculator
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For informational purposes only. Does not constitute financial advice. Rates may vary based on your actual contracts.
Snowball method: psychology before math
Popularized by Dave Ramsey, the snowball method has you list your debts from smallest to largest balance, regardless of interest rate. You pay the minimum on everything, then throw every extra dollar at the smallest one. Once it is gone, you "roll" that payment onto the next one. The advantage? Quick wins that keep you motivated. The cost? You may pay more in total interest if your smallest debts carry low rates while your largest debts carry high rates.
Avalanche method: the math wins
The avalanche method targets the debt with the highest interest rate first. By reducing the debt that accumulates interest fastest, you mathematically minimize the total interest paid over the entire repayment period. The avalanche is almost always cheaper than the snowball — sometimes by a few dozen dollars, sometimes by thousands, depending on your debt profile. The difference is most pronounced when interest rates vary widely across your debts.
How the month-by-month simulation works
Each month, the calculator:
- Calculates monthly interest for each debt:
interest = balance × annual rate / 100 / 12 - Applies the minimum payment to each debt (principal + interest until balance reaches zero)
- Directs the extra budget (plus freed minimums from paid-off debts) to the target debt according to the chosen method
- Repeats until all debts reach zero (maximum 600 months)
If a minimum payment does not cover the monthly interest, the debt grows (negative amortization). The calculator warns you in that case.
Which method should you choose?
Neither method is universally superior in practice. If you struggle to stay motivated, the snowball may be worth the extra interest cost. If you want to optimize total payment, the avalanche is the right choice. Some people combine both: eliminate one or two small debts for a psychological boost, then switch to avalanche mode for the remainder.
What matters most is maintaining payments every month and maximizing the extra amount you put toward debt. The difference between methods is often smaller than the difference discipline makes.
Frequently Asked Questions
What is the difference between the snowball and avalanche debt payoff methods?
The snowball method targets the debt with the smallest balance first, regardless of interest rate. Each debt eliminated frees its minimum payment to roll onto the next. The avalanche method targets the highest interest rate first, minimizing total interest paid. In general, the avalanche costs less, but the snowball delivers quick wins that help sustain motivation.
How is the month-by-month payoff calculated?
Each month, monthly interest is calculated for each debt (balance x annual rate / 12). Minimum payments are applied to all debts first. The extra budget (plus freed minimums from paid-off debts) is entirely directed to the target debt. The simulation runs until all debts reach zero, up to a maximum of 600 months.
What happens if my minimum payment is less than the monthly interest?
If the minimum payment does not cover the monthly interest, the debt grows each month — this is called negative amortization. The calculator detects this and displays a warning. You would need to increase your minimum payment or extra budget to make the debt payable within the simulation period.
Which method should I choose for my situation?
The avalanche is mathematically superior for total interest paid. The snowball can be better for motivation, especially with several small debts. Many people combine both: knock out one or two small debts for a psychological boost, then switch to avalanche mode. What matters most is consistency — maintaining the payments every month and putting as much as possible toward debt reduction.
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