Debt Payoff Calculator: Watch Avalanche and Snowball Race to Zero

By Tom, CPA · Updated October 25, 2026

TL;DR: Enter up to four debts and the total you can pay each month. The calculator runs both the avalanche (highest rate first) and snowball (smallest balance first) methods month by month and shows time to debt-free, total interest, and when your first debt disappears.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Arguing about debt payoff methods is fun. Measuring them is more useful. This calculator takes your actual balances, rates and minimums, applies the same monthly budget under both popular methods, and reports the results side by side.

It's deterministic: the same inputs always produce the same outputs. It runs entirely in your browser; nothing you type is sent anywhere. For the reasoning behind each method, read debt avalanche vs snowball.

CPA Warning Label: A calculator can show you the finish line. It cannot stop you from buying a jet ski on the way there.

Inputs

• Balance for each debt, in dollars. Leave unused rows at 0.
• APR as a percentage (for example, 24 for 24%). The calculator applies APR ÷ 12 each month, a standard simplification. Real card interest is usually computed on average daily balances, so expect small differences from your statements.
• Minimum payment per month. Use your current statement minimum; card minimums often fall as balances fall, but holding them fixed keeps the comparison clean.
• Total monthly amount you'll put toward all debts combined. It must cover the sum of the minimums, or the calculator returns no result.

How the schedules work

Each month the calculator does the same four steps for both methods:

1. Add one month of interest to every open balance.
2. Pay the minimum on every open debt (or the remaining balance, if smaller).
3. Send everything left over to the current target debt; if it's paid off, the remainder spills to the next target in the same month.
4. Repeat until every balance hits zero, or stop after 100 years and report no result.

The only difference is the target order. Avalanche sorts by APR, highest first (ties go to the smaller balance). Snowball sorts by balance, smallest first (ties go to the higher rate). When a debt is paid off, its minimum payment is automatically freed for the next target, because the total monthly amount stays constant. That rollover is what makes both methods accelerate.

Interest saved

The extra interest with snowball output is snowball interest minus avalanche interest. It's zero or positive in typical cases, because sending extra money to the highest rate first minimizes interest. If it's small, pick whichever method you'll stick with. If it's large, the avalanche earns its reputation.

Illustration (the default inputs, all assumptions): debts of $1,200 at 18%, $6,000 at 24%, $9,000 at 7% and $4,000 at 11%, with minimums of $40, $150, $250 and $120, and $1,000 a month in total. Results: both methods finish in 23 months. The avalanche pays about $2,292 in interest and the snowball about $2,719, a gap of about $427. The snowball pays off its first debt in month 3; the avalanche's first payoff comes in month 12.

Now try raising the monthly amount to $1,200 and watch both timelines shrink, along with the gap. Extra dollars are the most powerful input on the page; the method is second.

Comparison output

Caveats

• Rates are held constant. Promotional 0% balances that later reset aren't modeled; for those, run the calculator with the post-promo rate or treat the promo end date as a deadline.
• Fees, late charges and new purchases aren't included. The model assumes the card is no longer being used.
• Minimums are fixed. Real minimums often decline with the balance, which slows payoff if you only pay the minimum but doesn't matter when you keep the total payment constant, as this tool assumes.
• Variable-rate loans, student loan income-driven plans and mortgages behave differently; see student loans and FIRE.
• This is an educational model, not a lender's payoff quote. Ask the lender for an exact payoff amount before sending a final payment.

After you're debt-free

If the numbers look impossible, that's information too. The FTC suggests calling creditors early to ask about lower rates or a payment plan, and warns that debt settlement can damage credit and that forgiven amounts may be taxable. A nonprofit credit counselor is another option; the FTC's guidance on vetting one is listed in the sources below.

The day the last balance hits zero, the whole monthly amount becomes available. A household paying $1,000 a month toward debt can redirect that same $1,000 to savings without changing its lifestyle at all. That's the real prize. Point it at an emergency fund first if yours is thin, then at investing. Our savings rate calculator shows how much faster financial independence arrives when that money starts compounding for you instead of for a lender.