Loan Repayment Schedule Example and Calculator

This loan repayment schedule calculator estimates the fixed monthly payment and total interest for a fully amortizing loan when you enter the principal, annual APR, and term in years. Its example schedule shows how each payment is divided between interest and principal, and how the balance declines over time.

Formula

The schedule assumes equal monthly payments and a fixed interest rate. First calculate the monthly rate, then calculate the payment needed to repay the principal over the number of monthly periods:

• Monthly rate: r = APR / 1200, where APR is entered as a percentage per year.
• Number of payments: n = years × 12.
• Monthly payment: M = P × r / [1 − (1 + r)⁻ⁿ]. The calculator displays the result to the nearest cent.
• Total interest: I = (M × n) − P, using the displayed, cent-rounded payment.

Here, P is the starting loan principal in dollars, r is the monthly rate as a decimal, n is the number of monthly payments, M is the monthly payment in dollars, and I is total interest in dollars. The calculator’s total-interest figure is a useful summary, but it does not provide a separate row for every month.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed, 8% APR, and a five-year term—the schedule has 5 × 12 = 60 monthly payments. The monthly rate is 8 / 1200 = 0.0066667, or about 0.66667% per month.

Substituting the values into the payment formula gives M = 20,000 × 0.0066667 / [1 − (1.0066667)⁻⁶⁰], which rounds to $405.53 per month. Total interest is calculated using that rounded payment: $405.53 × 60 − $20,000 = $4,331.80. The corresponding total of scheduled payments is $24,331.80.

A few illustrative rows show how amortization works. In the first month, interest is approximately $20,000 × 0.0066667 = $133.33. Subtracting that from the $405.53 payment leaves about $272.20 to reduce principal, so the remaining balance is about $19,727.80. In the second month, interest is calculated on that lower balance: approximately $131.52. The principal portion is then about $274.01. Values can differ by a cent from a lender’s detailed schedule because lenders may calculate daily interest or apply rounding at different stages.

By the final payments, the outstanding principal is smaller, so less of each fixed payment goes to interest and more goes to principal. A real schedule may adjust the final payment slightly to clear any small balance caused by rounding.

How to Read a Repayment Schedule

A full repayment schedule, also called an amortization schedule, usually has one row per payment. Common columns include the payment number or date, opening balance, payment amount, interest charged, principal repaid, and closing balance. For each row, the opening balance is the previous row’s closing balance.

• Interest: opening balance multiplied by the applicable interest rate for the period.
• Principal: payment minus interest, assuming no other amount is included in the payment.
• Closing balance: opening balance minus principal paid.

This breakdown explains why a fixed payment does not mean a fixed amount of principal is repaid every month. Early payments generally include more interest because the balance is larger; later payments generally reduce principal more quickly. The exact sequence depends on the loan’s rate, payment dates, and calculation method.

When This Estimate Is Useful

Use the calculation to understand the basic payment structure of a fixed-rate, fully amortizing loan or to check the arithmetic in a quoted payment. Enter the amount actually financed as the principal, rather than assuming it is the purchase price: a financed fee or other amount may change the principal, while a down payment may reduce it. Use the APR and term supplied in the lender’s disclosure for a closer estimate. The neutral example figures above are inputs for illustrating the formula, not a statement about available loan terms.

The result is a model of scheduled payments, not a full account ledger. A lender’s schedule may include an initial partial period, a different day-count convention, payment-date effects, or a final adjustment. If payments are not monthly or the rate changes, this formula may not describe the actual schedule.

Common Misunderstandings and Limits

• APR is not entered as a decimal. Enter 8 for 8%, not 0.08. The formula converts the annual percentage to a monthly decimal by dividing by 1200.
• Total interest is not the total repaid. Add the principal to interest to get the modeled total payments. In this example, that is $20,000 + $4,331.80.
• The payment may not equal the whole bill. A mortgage payment, for example, may include separately assessed items such as taxes or insurance. They are not inputs in this calculator.
• Rounding matters. This calculator rounds the monthly payment to cents and then uses that displayed payment to calculate total interest. A lender may use unrounded intermediate values or a different posting method.
• Variable rates and extra payments change the path. A rate adjustment or payment above the scheduled amount changes future interest and balances; neither is represented by this fixed-payment estimate.

The formula also assumes every scheduled payment is made in full and on time, with no fees added to the balance and no payment holidays or other account changes. It does not determine whether a particular loan is suitable or whether an applicant qualifies.

Frequently Asked Questions

What is a loan repayment schedule?
A loan repayment schedule lists each planned payment and shows how much goes to interest and principal, along with the balance left afterward. It is often called an amortization schedule.

How do I calculate a monthly loan payment?
Convert the APR to a monthly rate by dividing the percentage by 1200, convert the term to months, and use the fixed-payment formula shown above. This calculator performs those steps and rounds the payment to cents.

Why does the interest portion fall over time?
For a fixed-rate amortizing loan, periodic interest is based on the outstanding balance. As principal is repaid and the balance declines, the interest charged per period generally declines too.

Does this schedule include fees, taxes, or insurance?
No. The calculator includes only principal and interest under its assumptions. Ask the lender for a payment breakdown that identifies any additional amounts relevant to the loan.

Why might my lender’s payment differ by a few cents?
Rounding, payment dates, daily-interest calculations, an initial partial period, or a different final-payment adjustment can produce small differences. Check the lender’s disclosed calculation and payment schedule for the contractual figures.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are equal, monthly, and made at the end of each monthly period.
• Interest compounds monthly at APR / 12.
• Fees, taxes, insurance, PMI, escrow, extra payments, and payment-date variations are not included.

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

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2