Debt Payoff Calculator: Avalanche vs Snowball

The difference between the two methods

Both approaches pay every minimum every month and put a fixed extra amount toward one debt at a time. The only thing that differs is which debt gets the extra. The avalanche aims it at the highest interest rate, which is mathematically optimal — every dollar goes where it kills the most interest. The snowball aims it at the smallest balance, clearing individual debts fastest and giving you a visible win early.

When a debt is cleared, its minimum payment rolls onto the next target on top of the extra. That rolling effect is what makes both methods accelerate, and it is why paying minimums alone takes so devastatingly long by comparison.

How big is the gap, really?

Smaller than the argument about it suggests. On the default figures above the avalanche saves a few hundred dollars over the whole payoff — real money, but not life-changing, and the two finish within a month or two of each other. The gap widens when your smallest balance also carries your lowest rate, because the snowball then spends months attacking cheap debt while an expensive card compounds behind it. Enter your own numbers and the calculator tells you which case you are in.

The honest conclusion, and the one the research supports, is that the method you actually complete beats the method that is theoretically optimal. If the difference on your numbers is under a few hundred dollars and early wins would keep you going, take the snowball without guilt. If the difference is thousands, the avalanche is worth the patience.

What actually moves the needle

Not the ordering — the extra payment. Doubling the extra monthly amount typically cuts both the timeline and the interest far more than choosing the better strategy ever will. If you want a shorter payoff, the lever is the amount, and the ordering is a rounding error by comparison. Try it: change the extra payment field before you change anything else.

Two other things beat both methods outright. A 0% balance transfer stops the compounding entirely for twelve to twenty-one months, though the transfer fee of 3% to 5% is real and the rate afterwards is usually punitive. And an employer match on retirement contributions is an immediate 50% or 100% return, which no consumer interest rate can match — capture the match first, then attack the debt.

If your income is irregular

Freelancers face a version of this problem that fixed-salary advice ignores. A month with three invoices paid and a month with none are not the same month, and committing to a fixed extra payment you cannot always make leads to missed minimums, which cost far more than any ordering decision. The workable approach is to set the extra payment at what a bad month can support, and treat good months as bonus principal on top. Keep your quarterly tax money separate from all of it — the IRS is not a creditor you can renegotiate with, and the underpayment penalty is charged at the federal short-term rate plus three points.

If you are carrying debt on a business card, the interest on the business-use portion is deductible on Schedule C, which quietly reduces its effective rate by your combined tax rate — often to below what a personal card at a lower nominal rate really costs you. That is a genuine reason to reorder, and it is the one exception where the avalanche ranking by headline rate misleads.

Frequently asked questions