Debt Payoff Calculator: What the Two Attack Orders Actually Cost

The only difference between the two methods is where the extra money goes

Both methods run the same machine. Every month, interest lands on each balance. Every line then gets its stated minimum, because missing one buys you a late fee and a penalty rate on top of the interest. Whatever you can still afford goes at one chosen line, and when that line reaches zero, its own minimum joins the pile aimed at the next one. Avalanche chooses the line with the highest rate. Snowball chooses the line with the smallest balance. That is the entire disagreement.

Which means the size of the pile is a bigger lever than the choice of target. Anyone comparing the two methods without also comparing a monthly amount is comparing the smaller of the two numbers.

A worked example built from published rates, not invented ones

Three balances, all with real numbers behind them. The rates come from the Federal Reserve's G.19 Consumer Credit release of 7 October 2026, the Terms of Credit table for August 2026 (preliminary): 22.36% is what credit card plans charged on accounts assessed interest, 21.19% is the all-accounts card rate, and 11.90% is a 24-month personal loan. The two card balances are the Federal Reserve's Survey of Consumer Finances for 2025, published 9 October 2026 - among families who reported carrying a card balance, the median was $3,100 and the mean $8,000. The card minimums use the formula Regulation Z prints for its own sample repayment disclosures (Appendix M2 to Part 1026): 2% of the outstanding balance, or $20, whichever is greater. The loan payment is an assumed fixed installment.

Read the interest column before you read the order of attack. In month one these three balances generate $243.48 - money that appears whether you have decided anything or not.

Now your own numbers

Type in each balance, its rate and the minimum your statement asks for, then put in the total you can genuinely send at debt every month. The calculator answers for both orders at once, in the same engine that produced the table above. It runs entirely in your browser: there is no account, no email prompt, and nothing is sent to this site or any other.

What the example says, including the part the usual advice skips

At $550 a month against $15,100 of debt, avalanche and snowball finish in the same month - month 38. Avalanche pays $5,318.63 of interest and snowball pays $5,430.31, a difference of $111.68 across 3 years 2 months. Snowball does buy one thing avalanche does not: its first line disappears in month 19 against month 24 for avalanche, and for some people a closed account is the only reason the plan survives autumn.

The comparison that matters is the next row down. Those same three balances, paid at exactly the stated minimums of $412 a month, take 4 years 11 months and $9,056.43 of interest. Adding $138 a month buys back 21 months and $3,737.80. That is the ratio of the two decisions: one is worth a few hundred dollars over three years, the other is worth years.

Both are true at the same time, and only one of them requires a spreadsheet.

Where the extra money comes from

The surplus is the hard part, and it is almost never found by budgeting harder in the abstract. It is found by opening one month of activity and marking everything that recurs - which is a twenty-minute job, not a lifestyle change. The 20-minute bank statement audit is the method this site uses, and it is written for exactly this purpose: producing a repeatable monthly number you can point at debt.

Two things that do not count as surplus. Do not take a new loan to pay an old one unless the written-out comparison shows a lower total cost, and do not free up money by stopping the minimum on a line you have not closed - that is a fee and a rate hike, not a payment.

When a minimum payment is not a payment

There is one line worth checking by hand before you trust any calculator. Multiply a balance by its APR and divide by 1,200: that is one month of interest. On $8,000 at 22.36% it is $149.07 - which is why the $160 minimum on it works, and a $140 minimum on the same balance would not. If the number the statement asks for is below the interest the month produces, the payment is not reducing the debt; it is buying time on it, slowly and at full price.

The calculator refuses to dress that up. When a budget cannot out-run the interest it prints "not at this budget" instead of a month count and "no total - it never ends" instead of an interest figure, names every line whose required payment had to be raised to cover interest, and gives the monthly amount below which at least one balance grows whatever you aim the rest of the money at. A fifty-year simulation of never getting ahead is not an answer, and it is not going on the page as one.

What paying it down does to the credit file

Both scoremakers define the same ratio. FICO: "Credit utilization rate is calculated by dividing an account's outstanding balance by its credit limit", worked as a $10,000 balance on a $20,000 limit giving 0.50. VantageScore works the same arithmetic smaller - a $200 balance on a $1,000 limit is 20%. So every dollar that leaves a card balance lowers that ratio, which is the part of the payoff that shows up on a report before the account is closed.

Two honest limits on that sentence. Neither publisher states a target percentage on the pages quoted here, so anyone telling you to hit a specific number is quoting their own product, not the score model. And a paid-off card whose account stays open keeps its credit limit working for the ratio, while the same card closed takes that limit out of the denominator - so the balance and the account status are two separate decisions.

Before you hand money to a settlement company

If a plan involves you paying less than you owe and someone negotiating the difference, two public documents are worth reading first. The IRS states in Topic No. 431 that where debt is cancelled, forgiven or discharged for less than owed, "the amount of the canceled debt is taxable" as a general rule, with exclusions for Title 11 bankruptcy and insolvency claimed on Form 982. The Federal Trade Commission's consumer alert of 26 March 2026 on debt relief puts the practical test bluntly: "only scammers will tell you to pay them upfront before they settle any of your debts."

Then run the same arithmetic the calculator runs. A settlement that writes off $3,000 of a $8,000 balance in exchange for $3,500 of payments and a reported delinquency is not obviously cheaper than the avalanche column - and you can compare them on this page in about ten seconds, which is more than most contracts deserve.

What this calculator assumes

• Interest is credited once a month at the APR divided by twelve. Card agreements compound daily, so a real card costs slightly more than this prints - treat the interest figures as a floor rather than a ceiling.
• Rates are fixed for the whole run. A promotional rate expiring, a penalty rate triggering or a variable index moving will change the answer.
• Accounts with two or three rates at once - Regulation Z's own example splits a $1,000 balance across 0%, 17% and 21% - are modelled here as separate lines. Give each rate its own row.
• The minimums you enter are the ones you actually pay, and payments land at the end of each month.
• No new purchases, no fees, no balance transfers, no skipped months. The last one is the assumption real life breaks, which is why the $138-a-month version of this plan has to be a number you can repeat in a bad month.

The short version

Pick the order you will still be following in month eight, then fight for the monthly amount. On the published rates above, the order is worth $111.68 and the extra money is worth $3,737.80 and 21 months.