Debt snowball vs avalanche calculator: what each method does, the sample case where they finish in the same month, and how big the gap really is

There are two well-known orders for paying off several debts at once, and the argument about which is better has gone on for years. The arithmetic is not in dispute: paying the highest rate first always costs the least interest. The argument is about people. This page says what each order does, what the regulator says each trades away, and then runs one sample set of debts through both so the size of the gap is a number rather than a slogan.

The two orders

Both methods start from the same place. Every debt gets its minimum payment every month. Whatever extra you can afford on top of all the minimums goes to one target debt. When the target is cleared, its minimum joins the extra, and the larger pool moves to the next target. The two methods differ only in how the target is chosen.

Snowball: the smallest balance first. The US Consumer Financial Protection Bureau describes it as an approach that "focuses on your smallest debt. The goal is to get rid it as soon as possible", and notes the trade-off: "you'll see progress quickly as you pay off smaller debts. However, you may end up paying more in the long run, as you won't be focusing on the larger or more costly debts" (source 1). Avalanche: the highest interest rate first. The CFPB calls this the highest interest rate method, which "focuses on your debts like credit card and student loan debts with the highest rate of interest", and says of it: "While it may not feel like you're making progress, this method will help you eliminate your costliest debts first, which can save you money in the long run" (source 1).

That is the whole of the disagreement. Avalanche is cheaper. Snowball clears the first account sooner, which some people need in order to keep going. The CFPB does not pick one; it says to weigh the two against what motivates you.

The sample case

The free calculator and the Bindler workbook share one illustrative set of four debts: a credit card of 3,100 at 21.99% with a 95 minimum, a car loan of 7,400 at 4.9% with a 240 minimum, a personal loan of 5,200 at 11.5% with a 160 minimum, and a student loan of 12,000 at 6.2% with a 185 minimum. Total owed 27,700, total minimums 680 a month, plus an extra 250 a month, so 930 goes out every month until debts start to clear. Both schedules were recalculated with a formula engine and matched to an independent Python replica before listing (source 2).

• Snowball: debt-free in month 34. Total interest 2,969.08. Total paid 30,669.08.
• Avalanche: debt-free in month 34. Total interest 2,928.87. Total paid 30,628.87.
• Difference: 40.21 of interest, and zero months.

Three findings sit in those lines. First, avalanche is cheaper, as it always is. Second, on these numbers the gap is 40 over almost three years, because the smallest debt here (the credit card) is also the highest-rate debt, so the two orders start identically and only diverge on the second target. Third, the order barely matters next to the extra payment: 250 a month on top of the minimums is what turns a set of debts that would run for years into a 34-month plan. Change the extra to zero in either tool and watch the month count, not the method, move.

Where the orders differ widely is when a large low-rate debt is also the smallest, or when a small debt carries a very high rate but is not the smallest. The free calculator answers that for your own list in a second.

What the order does not fix

Neither method changes what you owe or the rates you pay. Three things do, and they come before choosing an order: stop adding to the balances, check whether any high-rate balance can be moved to a lower rate, and confirm the minimums and rates on each statement rather than from memory. A payoff plan built on a wrong rate is wrong in the same direction every month.

An overpayment on a mortgage competes for the same extra money; the mortgage overpayment guide covers when that is the better use.

Run your own numbers

The free debt payoff calculator takes up to six debts and your extra monthly payment and returns the payoff month, total interest and total paid under snowball and under avalanche, in your browser with no sign-up. It gives the two headline lines and the difference, nothing else.

The Personal Finance Workbook shows the working: a Snowball sheet and an Avalanche sheet of 240 months each, every open debt charged interest on its opening balance, every minimum paid, the extra pool sent to the target debt, and a Payoff plan sheet with months to debt-free, total interest and total paid under each method and the difference. It also carries a Budget sheet (planned against actual per category, surplus and savings rate) and a Net worth sheet (assets and debts by month with the change). Live formulas, no macros, no locked cells, Excel and Google Sheets. $12, one price.

The sample debts are illustrative; replace them. Arithmetic on your own numbers, not financial advice.

Sources

1. Consumer Financial Protection Bureau, "How to reduce your debt", 16 July 2019: https://www.consumerfinance.gov/archive/blog/how-reduce-your-debt/

2. Bindler, Personal Finance Workbook specification, Guide sheet and verification log (products/personal-finance/spec.json, build.py and verify.py), figures as listed 27 September 2026; the free calculator is checked against the same figures by products/personal-finance/verify_app.js.

Last checked against the sources on 28 September 2026.