Debt snowball calculator

The snowball clears your smallest balance first. This runs it against the avalanche on the same debts and tells you the two things that decide the choice: what the snowball costs in extra interest, and how much sooner your first debt disappears.

How the math works

The snowball and the avalanche run the exact same machine. Both pay the minimum on every debt, then throw whatever is left of your budget at one target. They disagree on which debt gets the extra.

Each month, interest accrues on every balance at its APR divided by 12. Minimums go out first. The leftover — your extra — lands entirely on the target. When a debt clears, its freed-up minimum joins the extra, so the amount hitting the next target grows. That growing payment is the "snowball," and it runs identically under either order. Only the target changes.

Picking by smallest balance ignores rate on purpose. It clears whole accounts fast, which is the point — one fewer statement, one fewer minimum, one visible win. The cost is that it leaves your highest-rate balances accruing longer than they would under the avalanche, which always targets the most expensive debt first. So the snowball trades interest for momentum. This calculator measures both sides of that trade instead of picking a winner for you.

Worked example

Take a household carrying three debts and putting $1,500 a month toward all of them combined:

• A credit card: $6,500 at the U.S. average APR of 22.76%.
• A student loan: $27,000 at the 2024–25 federal undergraduate rate of 6.53%.
• An auto loan: $32,000 at the average new-car rate of 8.40%.

Here the credit card is both the smallest balance and the highest rate, so both methods kill it first — the first debt is gone in month 14 either way. After that they split. The snowball goes card, then the $27,000 student loan, then the $32,000 auto loan. The avalanche goes card, then the auto loan (8.40%), then the student loan (6.53%).

Both clear the whole $65,500 in 52 months. The snowball pays $12,231.33 in interest; the avalanche pays $11,753.06. So the snowball costs $478.27 more, and finishes the same month. Over more than four years, that is under ten dollars a month for the smallest-first ordering. On this debt mix, momentum is nearly free.

Now move the numbers so the biggest balance is also the most expensive. Put the 22.76% rate on the $32,000 balance and the 6.53% rate on the $6,500 one, same $1,500 budget. The snowball still clears the small balance first — first win in month 13. The avalanche, chained to that $32,000 high-rate balance, doesn't clear anything until month 46. The snowball buys a first win 33 months sooner. It also now costs $14,094.48 more in interest. The early win and its price move together: the bigger the head start, the more you are paying for it.

When this calculator is wrong

The arithmetic is exact. Where a snowball calculator misleads is in what it leaves out — usually on purpose, because most of them are selling the method.

• It hides the price unless you make it show one. A calculator that only runs the snowball reports a debt-free date and an interest total with nothing to compare them to. The number that decides the choice is the gap to the avalanche. On the worked example that gap is $478.27 — trivial. In the rearranged case it is $14,094.48 — not trivial. Same method, same three balances. You cannot know which case you are in without running both, which is why this page does.
• The early win is the whole argument, and it is real. The snowball's defenders are not making a math claim; they are making a behavioral one. A debt you finish beats a cheaper one you quit. Gal and McShane, studying real debt-settlement data (Journal of Marketing Research, 2012), found that the fraction of whole accounts a person closed predicted whether they eliminated their debt — while the dollar balances of those accounts did not. If early wins are what keep you paying, the snowball's extra interest is the price of finishing, and finishing is worth more than the interest.
• It assumes fixed rates, fixed minimums, and no new borrowing. A variable-APR card, one new purchase, or a missed payment resets the whole schedule. The projection models a closed system; a real balance sheet is not one.
• Smallest-balance ordering can strand a genuinely expensive debt. If your smallest balance is a 6.53% loan and your largest is a 22.76% card, the snowball parks the expensive card in last place for years. When the rate spread is wide and sitting on a big balance, that is where the snowball's cost stops being a rounding error. Check the gap before you commit.

What to do with the result

Read the two numbers together. If the extra interest comes back small — a few hundred dollars over years — the snowball is a fine choice and the early wins are worth having. Pick the smallest-balance order, automate the $1,500 so the extra can't quietly get spent, and stop reopening the question. The gap between snowball and avalanche is smaller than the gap between paying the extra and not.

If the extra interest comes back large, you are in the wide-spread case, and the snowball is charging you real money for motivation. That can still be the right call if you honestly know you would stall under the avalanche — but decide it deliberately, with the number in front of you, not by default. Either way, the figure that moves your payoff date most is the size of the monthly budget. Raise that before you agonize over the order.

Common questions

What is the debt snowball method?

You list your debts from smallest balance to largest, ignoring interest rates. You pay the minimum on everything, then throw every spare dollar at the smallest balance until it clears. Then you roll its freed-up payment into the next-smallest, and repeat. The idea is that clearing whole accounts early builds the momentum to keep going.

Is the debt snowball better than the avalanche?

On interest, no — the avalanche always pays less, because it retires the highest-rate debt first. The snowball's case is behavioral: its early wins help some people stay on plan, and a method you finish beats a cheaper one you abandon. On these three debts the snowball costs $478.27 more and finishes the same month. The right method is the one you will actually run to zero.

How much does the debt snowball cost compared to the avalanche?

It depends entirely on your debt mix. When your smallest balance is also your highest rate, the two methods nearly tie — $478.27 over 52 months in the worked example. When a big balance carries the highest rate, the snowball can cost several thousand dollars, because it leaves that expensive balance accruing while it clears cheaper ones. Run both to see which case you are in.

Should I pay the minimum on my other debts while I attack the smallest?

Yes. Both methods require paying every minimum every month — that is what keeps the other accounts current. The strategy only governs where the extra money goes, not whether you skip payments. Miss a minimum and you add fees and penalty rates the calculator never sees.

Does the snowball pay off debt faster than the avalanche?

Usually not in total time. Because both methods spend the same budget, they often finish the same month; in the worked example both land at 52 months. What the snowball changes is when your first account disappears — month 14 here, and as much as 33 months sooner than the avalanche when the small debt carries a low rate.