Debt Payoff Sheet Calculator and How to Use It

A debt payoff sheet is a table for tracking balances, interest, payments, and estimated payoff dates across one or more debts. This calculator estimates how many monthly payments it takes to clear one debt when you enter its balance, APR, and planned monthly payment; it also shows the final payment amount and estimated interest.

Formula

This calculator assumes a fixed APR, monthly interest accrual, and a level payment at the end of each month. It estimates the number of full planned payments needed, then calculates the remaining balance after those payments and the final payment needed one month later.

• Monthly rate: r = APR / 1200, where APR is entered as a percentage per year.
• Months to payoff: n = ceil(round(−ln(1 − r × B / P) / ln(1 + r), 6)). This standard payment-count formula assumes the payment exceeds the interest charged each month.
• Balance after k payments: B_k = B × (1 + r)^k − P × ((1 + r)^k − 1) / r.
• Final payment: F = B_n−1 × (1 + r).
• Estimated total interest: I = P × (n − 1) + F − B.

Here, B is the current balance in dollars, P is the planned monthly payment in dollars, r is the monthly rate as a decimal, n is the estimated number of months, and F and I are dollar amounts. The final payment is not assumed to equal the regular payment: it is based on the remaining balance plus one month of interest.

Worked Example

Using the calculator’s defaults: balance B = $5,000, APR = 18%, and planned payment P = $250 per month.

1. Monthly rate: r = 18 / 1200 = 0.015, or 1.5% per month.
2. Estimated months: n = ceil(round(−ln(1 − 0.015 × 5,000 / 250) / ln(1.015), 6)) = ceil(25.91…) = 26 months.
3. After 25 regular payments, the estimated balance is $190.76, using B₂₅ = 5,000 × 1.015²⁵ − 250 × ((1.015²⁵ − 1) / 0.015).
4. Final payment after one more month of interest: F = $190.76 × 1.015 = $193.62, rounded to cents.
5. Estimated interest: I = $250 × 25 + $193.62 − $5,000 = $1,443.62.

The estimate therefore represents 25 planned payments of $250 followed by a final payment of about $193.62, for an estimated payoff time of 26 months. Actual statements may differ because balances and interest calculations can use daily accrual, payment dates, fees, or other account-specific terms.

Assumptions

• The APR remains fixed throughout the estimate.
• One payment is made at the end of each month; the first interest period is one month.
• Interest compounds monthly using APR / 12.
• Fees, penalty charges, taxes, changes in rates, and payment-date effects are not included.

What a Debt Payoff Sheet Tracks

A debt payoff sheet—sometimes called a debt repayment schedule or payoff tracker—organizes the information needed to monitor balances over time. A useful sheet usually has one row per debt and columns for the creditor or account label, current balance, APR, minimum due, planned payment, payment date, interest charged, and updated balance. A spreadsheet may also summarize total debt and estimated progress.

For several debts, calculate each account separately. A combined total alone can hide differences in APR, minimum payment, and repayment timing. A sheet is a planning aid, not an account statement: the lender or card issuer’s posted balance and payment requirements remain the authoritative figures for that account.

How to Use the Estimate

1. Enter the current principal or statement balance, the APR shown for that balance, and the monthly amount you plan to pay.
2. Check that the payment is greater than the first month’s estimated interest. At 18% APR on $5,000, for example, one month’s interest under this model is $75; a payment of $75 or less will not reduce the balance under the assumed schedule.
3. Read the payoff months, final payment, and total interest together. The final payment may be smaller than the planned payment because the remaining amount is paid off rather than another full installment.
4. Update the sheet with actual statement balances and payments over time. Recalculate after a balance change, a payment change, or an APR change.

The month count is rounded up so the schedule has enough monthly payment periods to clear the modeled debt. It is an estimate, not a promise that a lender will use the same count. If the payment does not cover monthly interest, the logarithm has no valid payoff result; a steadily accruing balance cannot be paid off with that amount under these assumptions.

Putting Multiple Debts on One Sheet

For a multi-debt sheet, enter a separate balance, APR, and planned payment for every account. Keep each account’s minimum due visible, and make sure the total planned payments are not mistakenly applied to each debt. The calculator here covers one balance at a time; it does not determine a payment allocation strategy or model transfers between accounts.

As a simple illustration, if a sheet lists a $5,000 balance and a separate $1,200 balance, do not combine them and apply one APR unless both balances genuinely share the same rate and repayment terms. Compute or track them separately, then add their projected interest or balances only when the periods and assumptions match. That avoids treating different rates as though they were one debt.

Common Sources of Difference

• APR versus monthly rate: Enter APR as a percentage such as 18, not 0.18. The formula divides the percentage by 1200 to produce a monthly decimal rate.
• Changing balances: New charges, cash advances, late fees, or credits can change the amount being repaid. This estimate assumes no new activity.
• Daily interest: Some accounts calculate interest based on daily balances and the timing of transactions. Monthly compounding is a simplified model.
• Payment timing and rounding: Actual payment dates and cent-level rounding can produce differences from a formula that treats each period consistently.
• Multiple APR categories: One account may have separate rates for different transaction types. A single APR cannot accurately represent all such balances.

Another common misconception is that the total interest shown is a fixed charge already owed. It is a projection of future interest under the entered payment and assumptions. Paying a different amount, making payments on different dates, or changing the balance changes the estimate.

Frequently Asked Questions

What is a debt payoff sheet?
A debt payoff sheet is a table or spreadsheet used to record debts and follow balances, payments, interest, and expected payoff progress. It can cover one account or list several accounts separately.

What should I include in a debt payoff spreadsheet?
Useful fields include the account label, balance, APR, minimum payment, planned payment, due date, actual payment, interest charged, and updated balance. Keep separate APRs or balance categories in separate rows.

How do I calculate how long debt will take to pay off?
For a fixed balance, fixed APR, and equal monthly payment greater than monthly interest, use the payment-count formula shown above. This calculator applies that formula and estimates the smaller final payment.

Why does the calculator say it cannot compute?
The planned payment may be too small to cover the first month’s modeled interest. In that case, the formula cannot produce a finite payoff period; verify the balance, APR, and payment inputs.

Is the payoff date exact?
No. It is a mathematical estimate based on monthly compounding and end-of-month payments. Account terms, daily interest, transaction activity, fees, and payment timing can change the actual payoff amount and date.

This result is an estimate for educational purposes, and the lender’s disclosure gives the exact figures.

Related

• Refinance Rates San Diego: Compare Costs and Payments
• Refinance Rates Los Angeles: 30-Year Loan Calculator
• San Diego 30-Year Refinance Rate Calculator

in bal | Current balance | $ | 5000 | 0.01 | 100000000
in apr | Interest rate (APR) | % | 18 | 0.01 | 100
in pay | Planned monthly payment | $ | 250 | 0.01 | 100000000
out mos | Estimated months to payoff | months | ceil(round(-ln(1 - (apr / 1200) * bal / pay) / ln(1 + apr / 1200), 6)) | 0
out final | Estimated final payment | $ | (bal * (1 + apr / 1200) ^ (mos - 1) - pay * ((1 + apr / 1200) ^ (mos - 1) - 1) / (apr / 1200)) * (1 + apr / 1200) | 2
out int | Estimated total interest | $ | pay * (mos - 1) + final - bal | 2