Amortization Table With Fixed Monthly Payments

An amortization table with fixed monthly payments shows, for each payment, how much goes to interest, how much reduces the loan balance, and what remains. This calculator estimates the level monthly payment and total interest from a loan amount, APR, and term; it does not generate every row of the table.

Formula

For a fixed-rate loan with equal monthly payments, the payment is calculated using the standard level-payment formula:

PMT = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]

• PMT is the monthly payment in dollars.
• P is the starting loan principal in dollars.
• r is the monthly interest rate as a decimal, calculated as APR ÷ 1200 when APR is entered as a percentage per year.
• n is the number of monthly payments, calculated as loan term in years × 12.

The total interest estimate is PMT × n − P. It uses the payment rounded to cents, as shown in the calculator. This assumes the scheduled payments repay the full principal and interest over the stated term.

Worked Example

Using the calculator’s default inputs—$20,000 principal, 8% APR, and a 5-year term:

1. Convert the annual percentage rate to a monthly decimal: 8 ÷ 1200 = 0.0066667.
2. Convert the term to months: 5 × 12 = 60 payments.
3. Substitute in the payment formula: $20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = $405.53, rounded to cents.
4. Calculate estimated total interest using that rounded payment: ($405.53 × 60) − $20,000 = $4,331.80.

The estimated scheduled payment is $405.53 per month, and the estimated total interest is $4,331.80. A lender’s actual schedule can differ if its payment dates, rounding conventions, fees, or loan terms differ.

Assumptions

• The interest rate is fixed for the full term.
• Payments are equal, made monthly, and the first payment is one month after the loan begins.
• Interest accrues monthly at APR divided by 12; the formula treats APR as a nominal annual rate.
• Fees, taxes, insurance, PMI, escrow, and any extra or missed payments are not included.
• The calculation assumes the loan is fully repaid by the end of the stated number of payments.

How to Read an Amortization Table

A full amortization table is a period-by-period record. Its typical columns include the payment number or date, beginning balance, scheduled payment, interest charged, principal repaid, and ending balance. The payment is split between interest and principal; the split changes even though the scheduled payment stays level.

For a simple monthly calculation, interest for a period is the beginning balance multiplied by the monthly rate. Principal repaid is the payment minus that period’s interest. The ending balance is the beginning balance minus principal repaid. In the first month of the example, estimated interest is $20,000 × 0.0066667, or about $133.33. Of the $405.53 payment, about $272.20 reduces principal, leaving about $19,727.80. Later, the balance is lower, so less of a level payment goes to interest and more goes to principal.

These row amounts are rounded illustrations. A lender may calculate interest using its own accrual and rounding methods, so do not treat an independently constructed table as an exact payoff statement.

When This Estimate Is Useful

The payment formula helps explain the relationship among principal, APR, and term, and provides a starting point for checking a proposed schedule. Changing one input at a time can show how the mathematical payment estimate changes. For example, a longer term generally spreads principal repayment over more payments, while interest continues to accrue; the calculator’s total-interest output makes that cost visible under its assumptions.

Enter the loan’s principal rather than the purchase price if the amount financed is different. Use the APR supplied for the specific loan, not a rate from an unrelated advertisement or an assumed market rate. Confirm with the lender whether any financed fees are already included in the principal. The calculator does not determine eligibility or tell you what amount is manageable.

Fixed Payments, Variable Rates, and Extra Payments

A fixed monthly payment does not necessarily mean every part of the loan is fixed. The formula assumes both a fixed rate and a regular payment schedule. With a variable rate, the interest portion can change when the rate changes, and the payment or payoff date may be recalculated under the loan’s terms. This calculator cannot model those changes.

Extra payments also change the schedule. If an extra amount is applied to principal, the balance may fall faster and later interest may be lower, but the outcome depends on how the servicer applies the payment and on any applicable loan terms. This page’s total interest assumes only the calculated scheduled payment. It does not account for extra payments, skipped payments, late payments, or a final payment adjusted to clear a small remaining balance.

Common Calculation Problems and Limits

• Mixing annual and monthly rates: APR entered as a percentage must be divided by 1200 to obtain the monthly decimal used here. Entering 8 instead of 0.0066667 as the monthly rate would produce a meaningless result.
• Using the wrong term unit: This calculator takes years and converts them to months. A term of 60 months should be entered as 5 years, not 60.
• Confusing payment with total borrowing cost: The monthly payment excludes costs not represented by the inputs, such as insurance or taxes. Total interest is not the same as total cash paid when additional costs apply.
• Expecting a full schedule: The outputs give payment and total interest, not every payment’s balance and allocation. A lender’s amortization schedule is needed for its exact row-by-row figures.

Cent rounding can cause small differences when a hand-built table is compared with a lender’s records. A lender may round interest each period or adjust the last payment. The formula is also not appropriate for interest-only periods, balloon payments, irregular payment intervals, or loans whose rate changes.

Frequently Asked Questions

What is an amortization table with fixed monthly payments?
An amortization table lists how each regular payment is divided between interest and principal and shows the remaining balance. “Fixed payment” means the scheduled payment amount stays level under the table’s assumed rate and terms; the interest and principal portions usually vary.

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

Why does more of each payment go to principal later?
Interest is calculated on the outstanding balance. As scheduled payments reduce that balance, the interest charge generally falls, leaving a larger part of the same level payment to reduce principal.

Does a fixed monthly payment include taxes and insurance?
Not in this calculation. It estimates principal and interest only. Taxes, insurance, PMI, escrow, and other costs must be checked separately in the relevant loan or payment disclosure.

Why might my lender’s amortization table differ?
Differences can result from the actual APR, financed fees, payment dates, daily versus monthly interest accrual, rounding methods, or adjustments to the final payment. Use the lender’s disclosure or servicing records for the loan-specific schedule.

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

Related

• Simple Interest Loan Amortization Table Calculator
• Amortization Table Software: Calculate Loan Payments
• Amortization Table Setup: Formula and Example

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 int | Total interest | $ | pmt * yrs * 12 - p | 2