Debt Payoff Calculator
Enter your credit cards and loans, add any extra you can pay each month, and this tool compares the two proven payoff strategies — avalanche (highest rate first) and snowball (smallest balance first) — showing your debt-free date and total interest for each. It works in any currency.
Avalanche vs snowball: what the calculator does
Both strategies rest on the same discipline: pay the minimum on every debt, then put every spare dollar — your extra payment plus the minimums freed up as debts get cleared — onto one target debt until it is gone, then roll everything onto the next. The only difference is which debt you target first:
- Avalanche — highest interest rate first. This kills your most expensive debt soonest, so the least interest accrues. Mathematically it is always the cheapest and never the slowest route to debt-free.
- Snowball — smallest balance first. You clear whole debts quickly, which is motivating and simplifies your finances, but you usually pay a little more interest because a high-rate debt may sit longer.
The tool runs a full month-by-month simulation of both and shows the real difference in time and interest for your numbers, so you can decide with evidence rather than a rule of thumb.
Why extra payments matter so much
Interest is charged on the balance that remains, so every extra dollar you pay stops accruing interest for the entire rest of the payoff. That compounding-in-reverse effect is why raising the extra-payment field even a little often shaves months off the plan and hundreds or thousands off the interest. If you get a windfall, throwing it at the target debt has an outsized effect.
Worked example
Say you have three debts — $6,000 at 24% (minimum $120), $3,000 at 18% (minimum $75) and $9,000 at 11% (minimum $180) — and you can pay $200 extra each month on top of the $375 in minimums. Both methods finish in a similar time because the budget is fixed, but the avalanche attacks the 24% card first and so pays noticeably less total interest, while the snowball clears the $3,000 debt first for an early win. Enter your own balances above to see your exact numbers.
Methodology & assumptions
Each month the calculator adds one-twelfth of the annual rate (APR) to every balance, pays the stated minimum on every debt, and applies all remaining money — your extra payment plus any minimums freed by cleared debts — to the target debt chosen by the selected strategy. It assumes a fixed monthly minimum (real card minimums are typically a percentage of the balance, which falls as you pay down, so actual payoff can take slightly longer), APR compounded monthly, no new spending on the debts, and no fees. It is a planning estimate, not a statement of your lender's terms. See our methodology and editorial policy.
Frequently Asked Questions
Which method should I choose?
The avalanche costs the least interest and is never slower. Choose the snowball only if the quick wins of clearing small debts help you stay consistent — the plan you actually follow beats the optimal one you abandon.
Does a balance transfer help?
Often, yes. Moving a high-rate balance to a lower- or 0%-intro-rate card means more of each payment hits principal. Weigh the transfer fee against the interest saved — a dedicated balance-transfer calculator is on our list of related tools.
What counts as a "minimum" here?
Enter the fixed amount you will pay on each debt every month. The extra-payment field is anything above those minimums; that is the money the strategy concentrates on one debt at a time.
Turn a lump sum into a plan
See how a single extra payment or a windfall changes your debt-free date — just raise the extra-payment field above.
Then plan what comes next →Related calculators
Sources
The avalanche and snowball methods are widely documented debt-repayment strategies; the calculator uses standard reducing-balance interest math. Figures are estimates for planning, not a statement of any lender's terms — confirm minimums and rates on your statements. See our methodology and editorial policy.