Home Loan Amortization Table: Payments and Balance

A home loan amortization table shows each scheduled payment split between principal and interest, along with the remaining balance after each payment. Enter the loan amount, annual percentage rate (APR), and term to calculate the monthly payment and total interest; the table itself can then be built by applying the same monthly calculation to each payment period.

Formula

The calculator uses the standard fixed-payment loan formula. Let P be the starting principal in dollars, a the APR in percent per year, r = a / 1200 the monthly interest rate as a decimal, and n = 12 × years the number of monthly payments. The monthly payment is:

M = P × r / [1 − (1 + r)⁻ⁿ]

Total interest over the scheduled term is calculated using the displayed payment rounded to cents: I = M × n − P. The calculator assumes the rate stays fixed and that all scheduled payments are made as planned. Its payment is principal and interest only, not a complete estimate of a housing payment.

Worked Example

Using the calculator’s default inputs: principal P = $20,000, APR a = 8%, and term 5 years.

• Convert the annual percentage rate to a monthly decimal rate: r = 8 / 1200 = 0.0066667.
• Convert the term to monthly payments: n = 5 × 12 = 60.
• Apply the payment formula: M = 20,000 × 0.0066667 / [1 − (1.0066667)⁻⁶⁰].
• Rounded to cents, the monthly payment is $405.53.
• Using that rounded payment, total interest is $405.53 × 60 − $20,000 = $4,331.80.

The figures are principal-and-interest estimates. The example is not a quote for a home loan.

Assumptions

• The interest rate is fixed for the full term.
• Payments are monthly and made at the end of each monthly period.
• Interest accrues monthly at APR divided by 12.
• Fees, taxes, insurance, private mortgage insurance (PMI), and escrow are not included.

How a Home Loan Amortization Table Works

An amortization table lays out the loan’s payment schedule one period at a time. For each month, it shows the payment, the portion that covers interest, the portion that reduces principal, and the balance remaining afterward. Early in a standard fixed-rate loan, the balance is relatively high, so more of the payment goes toward interest. As principal falls, the interest portion generally shrinks and the principal portion grows.

To create a row, multiply the balance before the payment by the monthly rate to find that month’s interest. Subtract that interest from the scheduled payment to find principal repaid. Then subtract principal repaid from the prior balance:

• Interest for the month: starting balance × monthly rate.
• Principal repaid: payment − interest for the month.
• New balance: starting balance − principal repaid.

For the example, the first month’s interest is about $133.33 ($20,000 × 0.0066667). With a $405.53 payment, about $272.20 reduces principal, leaving roughly $19,727.80. Actual lender schedules can differ by a few cents because of rounding and the lender’s payment and interest conventions.

Reading and Using the Table

Use the schedule to see how the balance changes over time, estimate the interest paid across the planned term, or check how much principal remains after a particular payment. A full schedule has one row per payment month. A shorter summary can show selected dates, such as the end of each year, but it should be calculated from the underlying monthly schedule rather than by dividing annual totals evenly.

To calculate the balance after k payments under the same fixed-rate assumptions, use:

B_k = P(1 + r)^k − M[(1 + r)^k − 1] / r

Here, B_k is the remaining balance in dollars, P is the original principal, r is the monthly rate, M is the monthly payment, and k is the number of payments already made. This formula assumes the payment amount and rate have not changed.

What the Estimate Leaves Out

A home loan payment shown in an amortization table is not necessarily the amount collected each month. A housing bill may also include items such as property taxes, homeowners insurance, mortgage insurance, or escrow deposits. These costs do not repay principal in the standard amortization formula, so they should not be mistaken for loan interest or principal.

Also, a fixed-payment table does not represent every loan structure. An adjustable rate can change future payments and interest allocation. Interest-only periods, balloon payments, payment pauses, fees added to the balance, or irregular payment dates can also make the actual schedule different. Check the loan’s disclosure or servicing records for its actual terms and schedule.

Common Calculation Mistakes

• Entering APR as a decimal: enter 8 for 8%, not 0.08. The formula converts percent to a monthly decimal rate.
• Confusing years and months: this calculator takes the term in years and multiplies it by 12. A 30-year term means 360 monthly payments.
• Assuming every payment goes to principal: interest is calculated on the outstanding balance first; only the remainder reduces principal.
• Adding housing costs to loan interest: taxes and insurance may affect the total bill but are not included in this principal-and-interest calculation.
• Expecting displayed rows to sum perfectly: rounding each row to cents can create small discrepancies compared with calculations made using unrounded values.

An extra principal payment, if permitted under the loan terms, can change subsequent balances and the payoff timeline. A schedule that assumes only the regular payment will not show that change; a revised schedule must account for when the extra amount is applied and how the servicer treats it.

Frequently Asked Questions

What is an amortization table for a home loan?
It is a schedule showing each payment’s interest and principal portions and the remaining loan balance over time.

How do I calculate the principal portion of a mortgage payment?
For a given month, subtract that month’s interest (prior balance multiplied by the monthly rate) from the scheduled principal-and-interest payment.

Why does more of my payment go to interest at the beginning?
Interest is calculated on the outstanding balance. The balance is usually largest early in a fully amortizing loan, so the interest charge takes a larger share of a level payment then.

Does this payment include property taxes and insurance?
No. The calculator estimates principal and interest only. Taxes, insurance, PMI, escrow, and fees are not included.

Can I use this table for an adjustable-rate loan?
Only for a period during which the rate and payment assumptions remain unchanged. A rate adjustment can change the interest charge, payment, and future balance schedule.

This result is an estimate; 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