Debt Payoff Plan Calculator and Excel Guide

A debt payoff plan calculator estimates how long it may take to clear a balance and how much interest you may pay using a fixed monthly payment. Enter the balance, APR, and monthly payment to see the estimated payoff time and total paid; then use the steps below to build and track a multi-debt plan in Excel.

Formula

The calculator first finds the number of monthly payments required for a fixed-rate balance, then multiplies that whole number by the payment to estimate total paid. The monthly interest rate is r = APR / 1200, where APR is entered as a percentage per year. Months = ceil(round(−ln(1 − r × balance / payment) / ln(1 + r), 6)). Total paid = monthly payment × months. Estimated interest = total paid − starting balance.

• Balance: starting debt principal, in dollars.
• APR: annual percentage rate, entered as a percentage.
• Monthly payment: the fixed amount paid each month, in dollars.
• Months: estimated number of monthly payments, rounded up to a whole month.
• Total paid and estimated interest: dollar estimates over those months.

Worked Example

Using the calculator defaults: balance = $5,000, APR = 18%, and monthly payment = $250.

1. Convert APR to a monthly rate: 18 / 1200 = 0.015, or 1.5%.
2. Substitute into the payoff formula: −ln(1 − 0.015 × 5,000 / 250) / ln(1.015).
3. Calculate the expression: −ln(0.7) / ln(1.015) ≈ 23.95 months; round up to 24 payments.
4. Total paid = $250 × 24 = $6,000.00.
5. Estimated interest = $6,000 − $5,000 = $1,000.00.

Assumptions

• The APR stays fixed throughout the estimate.
• Payments are made monthly at the end of each period.
• Interest compounds monthly at APR / 12.
• The calculation excludes fees, taxes, insurance, and other charges. It assumes the same payment each month and does not model a smaller final payment.

What You’ll Need

• Excel and a list of debts, with each current balance, APR, and minimum payment.
• Your planned monthly amount for debt payments, based on your own budget.
• Any relevant account terms, such as promotional-rate end dates or fees; the basic spreadsheet below does not automatically model changing rates or fees.

Step-by-Step

1. Create a debt table. In a blank worksheet, put headers in row 1: Debt, Balance, APR, Minimum Payment, Extra Payment, Total Payment, Monthly Interest, and Estimated Months. Enter one account per row, starting in row 2. Record APR as a percentage (for example, enter 18% rather than 18 if you plan to use it as a percentage value).
2. Enter the current figures. Use the latest balance and required minimum payment shown by each account. Keep dollar values as numbers, not text. If an APR varies, label it clearly and use the current rate only as a temporary estimate.
3. Set your overall payment amount. In a separate cell, such as J2, enter the monthly amount you intend to direct to all listed debts. Include the minimums for every debt in that total. This is a planning input, not a recommendation; keep it consistent with your actual budget and obligations.
4. Calculate interest and payment allocation. In G2 enter =B2*C2/12 to estimate one month of interest, assuming C2 holds APR as a percentage. In F2 enter =D2+E2. Copy these formulas down. For a simple minimum-only baseline, enter each minimum in D and zero in E. The amount remaining after all minimums is =J2-SUM(D2:D10) (adjust the final row). Do not allocate more than this remainder as extra payments.
5. Choose and record a payoff order. You can sort by balance for a balance-first sequence or by APR, highest to lowest, for a rate-first sequence. These are alternative tracking methods, not guarantees of a particular outcome. Keep paying every minimum. Put available extra money in the Extra Payment column for the first debt in your chosen order; once it is cleared, move that extra amount to the next debt.
6. Estimate one debt’s payoff time. Use the calculator above for each debt if the payment is fixed and exceeds its monthly interest. In Excel, you can also use =ROUNDUP(-LN(1-(C2/12)*B2/F2)/LN(1+C2/12),0) in H2. This returns an estimate in whole months. Excel will show an error if the payment does not cover interest; use the troubleshooting guidance rather than treating the error as a payoff date.
7. Build a month-by-month schedule. For a more useful multi-debt forecast, add a separate sheet with columns for Month, Starting Balance, Interest, Payment, and Ending Balance for each debt. For each month calculate interest as starting balance × APR / 12, then ending balance as starting balance + interest − payment. Never let the payment exceed the amount due; the final payment should be only the remaining balance plus that month’s interest. Carry each ending balance into the next month’s starting balance.
8. Check and update it monthly. Compare the forecast with statements and actual payments. Replace balances with current figures, update APRs and minimums when they change, and note any extra payment. Excel is a tracker and estimate, not a substitute for account statements or payment instructions.

Common Mistakes

Entering APR as 18 instead of 18% can make calculated interest one hundred times too high if the formula expects a percentage value. Another frequent error is using the total payment as the extra payment and adding minimums again, which double-counts cash. Do not omit minimums on debts outside the current target. Also avoid assuming that a fixed-payment estimate accounts for variable APRs, late charges, new purchases, or a different payment posting date.

Tips

Format balances and payments as currency and APR as a percentage; freeze the header row and use Excel’s filter controls to sort debts. Add a notes column for rate changes or promotional periods. Protect formula cells from accidental edits, and keep an untouched copy of the original plan. A chart of total remaining balances by month can make progress easier to review, but only update it from verified balances.

Troubleshooting

If Excel returns #NUM! or the calculator cannot compute a payoff time, check whether the monthly payment is greater than the first month’s interest (balance × APR / 12). If not, the balance will not decline under the fixed-payment assumptions. If the estimate differs from a statement, check the APR format, fees, payment dates, rounding, new transactions, and whether interest is calculated daily on the account. If the plan no longer fits the amount you can pay, update the budget figure and re-run the forecast rather than hiding missed or reduced payments. Contact the account servicer for account-specific balances, terms, and payment allocation details.

Frequently Asked Questions

Should I use the balance-first or APR-first order?
Either order can be tracked in Excel. Balance-first prioritizes the smallest balance; APR-first prioritizes the highest rate. The spreadsheet estimates results from the inputs and does not account for every account term.

Does Excel automatically know my minimum payments?
No. Enter the minimum shown by each account and update it when it changes. The formulas cannot retrieve account information.

Why does the forecast show a different payoff date?
The estimate assumes fixed monthly rates and payments. Actual interest timing, changing APRs, fees, payment posting, or new charges can change the result.

Can I include extra payments?
Yes. Record extra amounts separately from minimums, and model when each extra payment is made. Keep minimum payments in place for all accounts in the schedule.

What if I can only pay the minimum?
Enter the minimum as the payment to estimate the result under the fixed-rate assumptions. Check the account’s own disclosures for the exact terms and payoff information.

This result is an estimate for educational purposes; the account’s disclosures and servicer provide the exact figures.

Related

• Debt Payoff Planner Excel: Calculate Your Payoff
• Debt Payoff Planner Free? Estimate Your Payoff
• Debt Payoff Planner: Estimate Your Monthly Payment

in bal | Debt balance | $ | 5000 | 0.01 | 100000000
in apr | Interest rate (APR) | % | 18 | 0.01 | 100
in pmt | Monthly payment | $ | 250 | 0.01 | 100000000
out months | Months to repay | - | ceil(round(-ln(1 - (apr / 1200) * bal / pmt) / ln(1 + apr / 1200), 6)) | 0
out total | Total paid | $ | pmt * months | 2
out interest | Total interest | $ | total - bal | 2