Calculate Total Loan Payment: Formula and Example

This calculator estimates the total of your monthly loan payments from the amount borrowed, APR, and term. Enter those figures to see the monthly payment and total interest; multiply the rounded monthly payment by the number of months to get the total paid through scheduled payments.

Formula

For a fixed-rate loan with equal monthly payments, first calculate the monthly payment, round it to cents, then multiply it by the number of monthly payments:

Monthly payment = round[ P × r ÷ (1 − (1 + r)⁻ⁿ), 2 ]
Total loan payments = rounded monthly payment × n
Total interest = total loan payments − P

• P is the loan principal, or amount borrowed, in dollars.
• APR is the annual percentage rate entered as a percentage, such as 8 for 8%.
• r is the monthly rate as a decimal: APR ÷ 1,200.
• n is the number of monthly payments: years × 12.

The payment formula spreads repayment of principal and interest across the term. The total-payment figure is the sum of those scheduled payments, not the amount borrowed alone. The total-interest figure separates the estimated interest portion from the principal.

Worked Example

Using the calculator’s default values—$20,000 principal, 8% APR, and a five-year term—there are 5 × 12 = 60 payments. The monthly rate is 8 ÷ 1,200 = 0.0066667.

1. Monthly payment before rounding: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰] ≈ $405.527.
2. Rounded monthly payment: $405.53.
3. Total loan payments: $405.53 × 60 = $24,331.80.
4. Total interest: $24,331.80 − $20,000 = $4,331.80.

Because the calculator rounds the monthly payment to the nearest cent before multiplying, its total reflects 60 identical $405.53 payments. A lender’s final payment may differ by a few cents if its schedule adjusts the last installment to reconcile daily accrual or rounding.

Assumptions

• The interest rate remains fixed throughout the loan term.
• Payments are equal monthly installments, paid at the end of each monthly period.
• Interest is modelled monthly at APR ÷ 12; this is a standard estimate and may not match a lender’s precise accrual method.
• Fees, taxes, insurance, PMI, escrow, late charges, and optional add-ons are not included.

What the Total Includes

“Total loan payment” can mean either one installment or the sum of all installments. Here, the headline result means the scheduled amount paid over the full term: monthly payment multiplied by the number of months. The monthly payment is shown separately, so the two meanings are not confused.

For an amortizing loan, each regular payment generally covers interest accrued for that period and repays some principal. Early payments on a longer loan can contain a larger interest share because the outstanding balance is initially higher. As the balance declines, the interest portion usually falls and more of each level payment goes toward principal. The total-interest estimate makes the cumulative cost of that interest visible.

The total is not necessarily every dollar a borrower might pay in connection with borrowing. If fees are added to the principal, the amount financed may be greater than the cash received. Separately billed charges, such as insurance or taxes, are outside this formula unless included in the loan amount or entered through a separate calculator input.

When to Use the Estimate

Use this calculation to understand the arithmetic of a fixed-rate, fully amortizing loan when you know its principal, APR, and term. It can also help you see how the payment count affects the total: a longer term means more monthly payments, while a different principal or APR changes the payment calculation. Treat the figures as estimates, not as a quote or a judgment about whether borrowing is appropriate.

For a useful estimate, enter the amount actually financed rather than assuming it equals the advertised purchase price. Use the APR and term shown in the lender’s disclosure or quote. APR is a yearly percentage measure, but the calculator converts it to a monthly rate by dividing by 12. It does not independently determine how a lender handles fees or calculates APR.

Common Mistakes and Limits

• Using the interest rate as a decimal in the APR field: enter 8 for 8%, not 0.08. The formula divides the percentage by 1,200.
• Mixing years and months: this calculator asks for years and converts them to months. Do not enter 60 to represent a five-year term; enter 5.
• Multiplying an unrounded payment: this calculator rounds the installment to cents first, then multiplies. A calculation using extra unrounded digits can produce a different total.
• Assuming every loan has level payments: variable rates, interest-only periods, balloon payments, irregular schedules, and changing payment amounts do not follow this formula throughout the full term.
• Confusing total payments with total interest: total payments include repayment of principal as well as interest. Subtracting the original principal gives the calculator’s estimated interest.

A zero interest rate is not allowed in this calculator because its payment expression divides by the monthly rate. For a genuinely interest-free loan with equal payments, the basic arithmetic is principal divided by the number of payments, but fees or other contract terms may still affect the amount paid.

Frequently Asked Questions

How do I calculate the total amount paid on a loan?
Calculate the fixed monthly payment, round it to cents, and multiply by the number of monthly payments. This estimate uses the APR-based amortization formula shown above.

Is total loan payment the same as total interest?
No. Total loan payments include both principal repayment and interest. In this calculator, estimated total interest equals total payments minus the original principal.

Does a longer loan term always reduce the total paid?
No. The monthly payment may change with the term, but a longer repayment schedule has more payments and can increase cumulative interest under the same fixed-rate assumptions. The calculator estimates the figures for the specific inputs provided.

Does this result include fees and insurance?
No. It includes only scheduled principal-and-interest payments calculated from the entered amount, APR, and term. Check the lender’s disclosure for any separately charged costs or amounts financed.

Why might a lender’s total differ from this estimate?
The actual schedule can use different rounding or interest-accrual conventions, include financed fees, or end with an adjusted final payment. Compare the inputs and payment schedule with the lender’s disclosure.

This is estimate arithmetic for education, not financial advice; 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 | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out tot | Total loan payments | $ | pmt * yrs * 12 | 2
out int | Total interest | $ | tot - p | 2