Debt Payoff Calculator

About this calculator

This calculator compares two popular debt payoff strategies — snowball and avalanche — so you can see which clears your debts faster and how much interest each approach costs. Enter each debt's balance, interest rate, and minimum payment, then add any extra amount you can put toward debt each month.

How to read your results

The headline figures show months to debt-free and total interest paid under each strategy. Avalanche will always pay equal or less interest than snowball, because it attacks the highest-rate debt first; the difference widens when rates vary widely. The payoff order shown is the sequence in which debts reach zero. The balance chart traces the total remaining debt month by month for both strategies. If the calculator reports "never pays off," at least one debt's minimum payment is too low to cover its monthly interest — you'll need to increase that minimum or add extra monthly funds.

Worked example

Two debts: a credit card with a 5,000 balance at 22% APR and a 120 minimum, plus a car loan with a 2,000 balance at 8% APR and a 60 minimum. An extra 100 per month is available.

Snowball clears the car loan first (smaller balance), finishing in 33 months with 2,187 in total interest. Avalanche targets the credit card first (higher rate), finishing in 32 months with 1,787 in total interest — saving 400 in interest and one month.

Frequently asked questions

Which strategy saves more money?

Avalanche always pays equal or less total interest than snowball, because it eliminates the highest-rate debt first. The gap can be hundreds or even thousands depending on how different the rates are. Snowball may feel more motivating because you clear small debts quickly and see wins sooner.

How does the extra monthly amount work?

Each month, all minimums are paid first. The extra amount — plus the freed minimums of any previously paid-off debts — is then applied in full to the current target debt. When that debt clears, its minimum joins the pool for the next target. This cascading rollover is what dramatically shortens payoff time.

What does "never pays off" mean?

It means at least one debt's monthly interest exceeds its minimum payment, so the balance grows every month no matter how long you wait. The fix is to increase the minimum payment for that debt, add extra monthly funds, or pay a lump sum to reduce the balance below the break-even point.

Does this include fees or penalties?

No — the simulation uses only balance, annual rate, and minimum payment. Late fees, annual card fees, or prepayment penalties are not modelled. If those apply, your actual payoff time and cost will be higher than shown.

Can I use this for student loans or mortgages?

Yes, any fixed-rate instalment debt with a steady minimum payment fits the model. Variable-rate debts will produce an approximate result based on the rate you enter today; update the rate as it changes to re-run the projection.

How it's calculated

Each simulated month runs in three steps. First, interest is accrued on every open debt using the simple monthly rate: monthly interest = balance × (APR / 12). Second, each debt's minimum payment is applied (capped at the remaining balance). Third, a rollover pool — the extra monthly amount plus the freed minimums of debts cleared in prior months — is directed to the single current target debt and cascades to the next if it clears. The snowball strategy orders debts by ascending initial balance, smallest first. The avalanche strategy orders debts by descending annual rate, highest first. Input order is the stable tiebreaker in both cases. A debt is marked "never pays off" when a complete month produces no reduction in its balance (monthly interest exceeds or equals the minimum payment). The comparison figures — interest saved and months saved — are the difference between the snowball and avalanche totals; they are set to zero if either strategy cannot fully pay off all debts.