How the debt payoff calculator works
The calculator builds a month-by-month plan from three things: your debts, the minimum payment on each, and the extra money you can add each month. Every month it:
- Adds interest to each balance: balance × APR ÷ 12.
- Pays the minimum on every debt, so nothing falls behind.
- Sends all the extra money to one debt, the first unpaid debt in your chosen order.
- Rolls payments over. When a debt is paid off, its minimum is not spent elsewhere. It joins the extra money for the next debt, so your payments grow as you go.
Interest this month = balance × APR ÷ 12
Target debt gets: its minimum + (budget − all minimums)
Your total monthly payment stays the same until the last debt is gone. That steady amount is what makes the plan speed up: in the final months, all of it goes to one debt.
Snowball vs avalanche
The two best-known plans differ only in the order you attack your debts.
| Debt avalanche | Debt snowball | |
|---|---|---|
| Pays extra to | The highest APR first | The smallest balance first |
| Total interest | Lowest possible | Same or higher |
| First debt cleared | Can take longer | As soon as possible |
| Best for | Saving the most money | Staying motivated |
The avalanche is the cheaper plan in maths terms. Each extra dollar removes the most expensive debt first. The snowball gives quick wins, which matters if motivation is your main problem. The Consumer Financial Protection Bureau (CFPB) describes both in its reducing-debt worksheet, and both use the same rollover idea.
You can also choose My order and use the arrows to put your debts in any order. For example, you might clear a loan from a family member first, or a debt with a co-signer.
Worked example: four debts
Say you owe:
| Debt | Balance | APR | Minimum |
|---|---|---|---|
| Visa card | $6,200 | 24.99% | $175 |
| Personal loan | $2,400 | 11.5% | $80 |
| Car loan | $14,500 | 7.9% | $390 |
| Store card | $3,100 | 29.99% | $95 |
The minimums add up to $740. You can pay $300 extra, so your budget is $1,040 a month.
Avalanche. The store card (29.99%) gets $395 a month and is gone in month 9. Its whole payment then moves to the Visa card, which is cleared in month 21. The personal loan follows in month 23 and the car loan in month 30. Total interest: $4,491.20.
Snowball. The personal loan, the smallest balance, goes first, in month 7. Then the store card (month 14), the Visa card (month 23) and the car loan (month 31). Total interest: $5,020.03.
Minimums only. Paying just the minimums and never rolling them over takes 69 months and costs $11,199.72 in interest.
| Plan | Debt-free in | Total interest |
|---|---|---|
| Avalanche | 30 months | $4,491.20 |
| Snowball | 31 months | $5,020.03 |
| Listed order (Visa first) | 31 months | $5,210.99 |
| Minimums only | 69 months | $11,199.72 |
The avalanche saves about $529 over the snowball here. Either plan saves more than $6,000 and over three years compared with paying the minimums.
How much the extra payment matters
Using the same four debts, here is what different extra amounts do. Even $0 extra helps, as long as you roll each cleared minimum into the next debt.
| Extra each month | Avalanche | Snowball |
|---|---|---|
| $0 (rolling minimums only) | 49 months, $10,029.11 | 49 months, $10,029.11 |
| $100 | 40 months, $6,881.09 | 41 months, $7,528.29 |
| $300 | 30 months, $4,491.20 | 31 months, $5,020.03 |
| $500 | 24 months, $3,442.51 | 25 months, $3,842.47 |
| $1,000 | 17 months, $2,248.56 | 17 months, $2,487.60 |
With no extra money, both orders happen to target the same debts, so they tie. The first $100 of extra money saves over $3,000 of interest. The amount you can add is often a bigger lever than the order you choose.
Reading your plan
- The headline shows your debt-free date, or the time it takes if you leave the start month blank.
- This month tells you exactly where to send the extra money right now.
- The comparison table shows all three orders and the minimums-only path, so you can see what your choice costs or saves.
- The chart shows what you still owe on each debt at the end of every year, with a dashed line for minimums only.
- The month-by-month plan lists what to pay on each debt, and what is left. Download it as CSV to track your progress in a spreadsheet.
Tips for sticking to the plan
- Stop adding new debt. The plan assumes no new charges. Put cards away while you pay them down.
- Automate the minimums on every debt so you never pay a late fee, then pay the extra by hand to the target debt.
- Keep a small emergency fund. A few hundred dollars set aside stops a car repair from going back on a card.
- Put windfalls on the target debt. Tax refunds, bonuses and gifts shorten the plan a lot.
- Ask for lower rates. A call to your card issuer can cut an APR, and a lower rate moves the date forward.
- Recheck it every few months. Update your balances and the calculator gives you a fresh plan.
If one cheaper loan could replace several debts, test it with the debt consolidation calculator. For a single card, the credit card payoff calculator shows the minimum payment trap in detail. To see how your debt compares with your income, use the debt-to-income ratio calculator, and track your progress with the net worth calculator.
Limits
This is a planning tool. It assumes fixed APRs, fixed minimum payments and on-time payments, with interest charged monthly. Credit cards charge interest daily and their minimums fall as balances fall, so real statements will differ a little. If you are behind on payments or contacted by collectors, the FTC’s guide on how to get out of debt and a nonprofit credit counselor can help.