A debt payoff calculator estimates how many months it will take to pay off your debts with a fixed monthly payment and how much interest you will pay. Formula: Same fixed-payment payoff model as the credit card tools: months = ceil(ln(payment/(payment-balance × r))/ln(1+r)), interest ≈ payment × months – balance. $12,000 at 12% APR paid at $400 a month takes 36 months and about $2,338.47 in interest.
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How to use the debt payoff calculator
- Enter your total debt.
- Enter the average APR, weighted by balance.
- Enter your monthly payment.
- Read the months to payoff and total interest.
How the debt payoff calculator works
The debt payoff calculator treats your debts as one balance at an average APR. Each month it adds interest at APR ÷ 12, subtracts your payment and counts the months until the balance reaches zero. The last payment is only the amount left, and total interest is the sum of each month’s charge.
- Interest each month = balance × APR ÷ 12
- Balance next month = balance + interest − payment
- The payment must be larger than the first month’s interest, or the debt never shrinks
Debt payoff calculator worked example
$12,000 of debt at an average 12% APR, paid at $400 a month, takes 36 months to clear and costs about $2,338.47 in interest. The first month’s interest is $120, so $280 of the first payment reduces the balance. Each month more of the payment goes to principal.
| Monthly payment | Months | Total interest |
|---|---|---|
| $300.00 | 52 | $3,401.60 |
| $400.00 | 36 | $2,338.47 |
| $500.00 | 28 | $1,790.94 |
| $700.00 | 19 | $1,229.68 |
Adding $100 a month to the $400 payment pays the debt off 8 months sooner and saves about $548 of interest.
Avalanche and snowball strategies
If you have several debts, keep paying the minimum on all of them and direct every extra dollar at one debt at a time:
- Debt avalanche: pay the highest-interest debt first. This minimizes total interest.
- Debt snowball: pay the smallest balance first. Each paid-off debt frees up its payment and gives a quick sense of progress.
When one debt is gone, add its payment to the next one. Your total monthly payment stays the same, but it attacks fewer debts, so the later ones fall quickly. The debt payoff calculator models the combined balance, so it shows your overall timeline at the average rate.
Finding money for extra payments
- Review your budget for subscriptions and spending you can cut.
- Use windfalls such as tax refunds, bonuses or gifts.
- Ask lenders about lower rates or hardship programs.
- Keep a small emergency fund so a surprise bill does not go back on a credit card.
Which debts to include
Include credit cards, personal loans, medical bills on payment plans and other consumer debts. Mortgages and student loans have long fixed schedules and special rules, so many people plan them separately. If your debts have very different rates, using one average APR in the debt payoff calculator gives a useful overall estimate but not an exact schedule; weight the average by balance for a better figure. For example, $8,000 at 18% and $4,000 at 6% average 14%, not 12%.
Estimates for education only, not financial advice. Your lender’s figures are final.
Tracking your progress
Write down each balance on the same day every month. Seeing the total fall keeps you motivated and quickly shows if new charges are creeping in. Rerun the debt payoff calculator whenever your balance, rate or payment changes, for example after a rate cut, a balance transfer or a raise that lets you pay more. Set up automatic payments for at least the minimum on every account so you never miss a due date; a late payment can add a fee and may trigger a higher penalty APR.
Once a debt is paid off, keep the account open if it has no annual fee, since closing it can reduce your available credit and raise your credit utilization. Then redirect the money you were paying toward savings, starting with an emergency fund of a few months of expenses, so a surprise bill does not send you back into debt.
Related converters and calculators
Related calculators:
- Credit card payoff calculator: cards
- Debt consolidation calculator: consolidation
- Budget calculator: budget
- Debt-to-income calculator: DTI
Sources
FTC: How To Get Out of Debt; CFPB: What is amortization?.
Formula and method
Same fixed-payment payoff model as the credit card tools: months = ceil(ln(payment/(payment-balance*r))/ln(1+r)), interest ≈ payment*months - balance.
General single-debt payoff. Not snowball/avalanche multi-debt sequencing.
Questions about this calculator
How long to pay off $12,000 at $400 a month?
About 36 months at 12% APR.
What is the debt avalanche?
Paying the highest-interest debt first to minimize interest.
What is the debt snowball?
Paying the smallest balance first for quick wins.
How do I average several APRs?
Weight each rate by its balance.
What if the tool says my payment is too low?
The payment does not cover monthly interest.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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