Debt Payoff Calculator
Becoming debt-free is faster when every spare dollar is aimed at the right account. This calculator lets you list all your debts, choose a single payoff strategy, and add an extra monthly amount, then simulates the months until everything is cleared. Pick Avalanche to attack the highest interest rate first and minimise cost, or Snowball to wipe out the smallest balance first for early momentum, and see the months, total paid, and total interest for your choice.
Formula
Monthly: Bᵢ ← Bᵢ(1 + rᵢ) − payᵢ; extra → first debt by chosen ordering
- Bᵢ
- Remaining balance on debt i
- rᵢ
- Monthly rate on debt i = annual rate ÷ 12 ÷ 100
- payᵢ
- Minimum payment, plus the extra if debt i is the current priority
- ordering
- Highest rate first (Avalanche) or smallest balance first (Snowball)
How it works
- Add each debt with its name, balance, interest rate, and minimum payment, then enter one extra monthly amount on top of the minimums.
- Select a strategy from the chip selector: Avalanche orders debts by highest interest rate, Snowball by smallest remaining balance.
- Each month the tool charges interest, pays every minimum, and funnels the extra into the top-priority debt; freed-up payments roll forward until all balances hit zero, then it reports the month count, total paid, and total interest.
Worked example
Two debts — $5,000 at 22% ($150 min) and $3,000 at 12% ($90 min) — with $300 extra each month, using Avalanche.
- Avalanche targets the 22% debt first while paying the minimum on the 12% debt.
- After the high-rate debt clears, its payment plus the extra rolls onto the 12% debt.
- The simulation finishes in 19 months with total interest of about $1,046.19 and total paid of about $9,046.19.
With the Avalanche strategy the debts are gone in 19 months, paying roughly $1,046.19 in interest; the Snowball ordering would take 20 months and cost about $1,357.14.
Frequently asked questions
- How do I choose between Avalanche and Snowball?
- Avalanche pays the least interest by clearing your highest-rate debt first, while Snowball gives faster visible wins by clearing the smallest balance first. Choose Avalanche to save money and Snowball if early progress keeps you motivated.
- What does the extra payment do?
- Every debt receives its minimum each month, and the extra amount is added to whichever debt your chosen strategy ranks first. When that debt is paid off, the extra plus its old minimum cascade onto the next debt.
- Can a single debt never get paid off?
- The simulation caps at 1,200 months. If your combined payments are too small to outpace the interest, balances may still remain when it stops, which is a signal that you need to increase your monthly payment.
- Does this compare both strategies at once?
- No — it runs the one strategy you select so you can focus on a single plan. To compare avalanche and snowball side by side across several cards, use the credit card payoff calculator instead.