Debt Payoff Calculator
The fastest way out of debt is a good plan. Compare the Avalanche and Snowball methods to see which one works best for you.
Enter your debts to see the results.
How this works
Simulates two payoff strategies side by side: avalanche (highest APR first) and snowball (smallest balance first). Every month, interest accrues on each remaining balance, then minimum payments are made on every still-open debt.
Total monthly outlay is held constant at the sum of all original minimum payments plus your extra payment: once a debt is paid off, its minimum doesn't shrink your total payment — it rolls into the pool that gets directed by the strategy's ordering, on top of the extra payment itself.
A debt is paid off, and drops out of the ordering, once its balance reaches zero; the simulation continues until every debt is at zero or 1,200 months (100 years) elapse.
Key assumptions
- Minimum payments are always paid on every open debt first; the strategy only decides where the leftover pool (extra payment plus any freed-up minimums from paid-off debts) goes.
- Interest accrues monthly on the current balance at each debt's entered APR.
- Default extra payment $200/mo across three example debts (credit card, student loan, car loan) — replace with your own.
What this leaves out
- Introductory/promotional APRs and rate changes over time — each debt's APR is held constant.
- Fees, minimum-payment increases, or lender behavior changes as balances shrink.
Related calculators
A worked example: three debts, two strategies
Take the three debts this calculator loads by default: a $5,000 credit card at 18.9% APR with a $100 minimum, a $25,000 student loan at 5.5% with a $250 minimum, and a $15,000 car loan at 4.2% with a $350 minimum. Total minimums are $700 a month, and the example adds $200 of extra payment on top, so $900 a month goes out the door every month until everything is clear.
Both strategies clear all $45,000 of principal in 58 months. Avalanche — highest APR first — pays $6,503 in interest. Snowball — smallest balance first — pays $6,575. The avalanche saves $71.
Seventy-one dollars over nearly five years is a smaller gap than the avalanche-versus-snowball argument usually implies, and it is worth understanding why: here the highest-rate debt is also the smallest balance, so both strategies attack the credit card first and only diverge afterward. The gap widens when a large balance carries the high rate, and it can reach hundreds or thousands of dollars. Run your own numbers before assuming either strategy matters much for your particular mix.
Frequently asked questions
Avalanche vs snowball — which one saves more?
Avalanche always saves at least as much interest, by construction: directing every spare dollar at the highest rate minimizes total interest, and no ordering can beat it. The real question is how much. On the example above the difference is $71 over 58 months. The spread depends entirely on whether your high-rate debts are also your large ones — if the biggest balance carries the highest APR, the two strategies coincide and there is nothing to choose; if a small balance carries a punishing rate, avalanche clears it early and snowball happens to agree.
So is snowball ever the right choice?
Yes, when the behavioral effect outweighs the interest. Snowball closes accounts sooner, and a plan you stay on beats a mathematically optimal plan you abandon. Compute both here: if the gap is tens of dollars, pick whichever you will actually follow; if it is thousands, the interest argument should probably win. Let the size of your own gap decide rather than the general argument.
What happens to a debt's minimum payment once it is paid off?
It stays in the pool. Total monthly outlay is held constant at the sum of all original minimums plus your extra payment, so when a debt clears, its freed-up minimum rolls into the pot directed by the strategy rather than reducing what you pay. This is the mechanism that makes both strategies accelerate — it is why $900 a month clears $45,000 of principal plus $6,503 of interest in 58 months rather than dragging on at the original minimums.
Should I pay off debt or invest instead?
Compare the debt's APR to the return you would realistically expect, after tax and net of fees. A guaranteed 18.9% return from clearing a credit card is not available anywhere in public markets, so that debt wins easily. A 4.2% car loan against an expected 7% nominal equity return is a genuinely close call — close enough that risk tolerance, liquidity and whether the interest is deductible reasonably decide it. Capture any employer retirement match first regardless; an immediate 50-100% return beats every debt on this list.
Does this model promotional or introductory APRs?
No. Each debt's APR is held constant for the entire payoff, so a 0% balance transfer that reverts to 24% in eighteen months will be modeled far too favorably if you enter the promotional rate. If you are carrying promotional debt, enter the rate you expect to pay for most of the payoff period, or model the pessimistic case and treat any promotional saving as upside.
Sources
- How to reduce your debt
Consumer Financial Protection Bureau — checked 2026-08-12
Describes the highest-interest-rate ('avalanche') and smallest-balance ('snowball') strategies this calculator lets you compare.
*The calculations provided are for illustrative purposes only and should not be considered financial advice. Please consult with a qualified financial professional before making any decisions.