Home Loan Payment Amortization Schedule Calculator

This home loan calculator estimates the fixed monthly principal-and-interest payment and total interest, then the schedule can be understood by tracking how each payment changes the balance. Enter the loan amount, annual APR, and term in years; the results are estimates based on a fixed rate and equal monthly payments.

Formula

The calculator uses the standard fixed-payment loan formula. It estimates the payment needed to repay the principal and interest over the specified number of monthly periods:

• Monthly payment: M = P × r ÷ [1 − (1 + r)⁻ⁿ]
• Total interest: I = M × n − P

Here, P is the starting loan principal in dollars, r is the monthly interest rate as a decimal (APR ÷ 1200), n is the number of monthly payments (years × 12), M is the monthly principal-and-interest payment in dollars, and I is the estimated interest paid over the full term. The calculator displays the payment to the nearest cent, then uses that rounded payment to calculate total interest.

Worked Example

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

1. Convert APR to a monthly decimal rate: 8 ÷ 1200 = 0.0066667.
2. Convert the term to payments: 5 × 12 = 60 monthly payments.
3. Substitute into the payment formula: M = 20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰].
4. Round the payment to cents: **$405.53 per month**.
5. Estimate total interest using the rounded payment: $405.53 × 60 − $20,000 = **$4,331.80**.

The example is a calculation, not a statement about available loan terms or rates. Your lender’s quoted APR and loan amount are the relevant inputs for an estimate.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are equal monthly payments, made at the end of each monthly period.
• Interest is modelled monthly at APR ÷ 12, with no separate daily-interest adjustment.
• The calculation excludes fees, taxes, homeowners insurance, mortgage insurance (PMI), escrow, and other charges; these are not part of the principal-and-interest payment shown.

How an Amortization Schedule Works

An amortization schedule breaks a loan into payment-by-payment entries. Each entry shows the payment, the amount applied to interest, the amount applied to principal, and the remaining balance. For a conventional fixed-rate calculation, the monthly payment is level, but its components change over time.

For each period, interest is calculated on the balance before that payment. The principal portion is the payment minus that period’s interest, and the balance falls by the principal portion. Early in repayment, the balance is larger, so more of a level payment goes to interest. As the balance declines, the interest charge generally shrinks and more of the payment reduces principal. The final payment may differ slightly in a real servicing record because of rounding or payment-date details.

For example, at the default monthly rate of 0.0066667, the first month’s estimated interest on $20,000 is about $133.33. Of the $405.53 payment, about $272.20 would reduce principal, leaving an estimated balance near $19,727.80. The figures are rounded for illustration; an actual schedule may carry more precision internally.

Reading the Results for a Home Loan

The monthly payment shown is principal and interest only. A home purchase payment may also include property-related charges or other amounts collected with the payment, while a lender’s loan estimate or billing statement may present those items separately or together. Do not treat this calculator’s payment as a complete housing-cost total.

Total interest is the sum implied by making the same rounded payment for every month of the stated term. It does not include upfront charges or other costs. The principal itself is not interest: in the example, the $20,000 borrowed plus $4,331.80 estimated interest produces $24,331.80 in payments under the calculator’s assumptions.

Common Mistakes and Limits

• Entering the wrong term unit: The input is years, not months. A 30-year term means 360 monthly payments.
• Confusing APR with monthly rate: Enter annual APR as a percentage, such as 8, not 0.08 or 0.6667. The formula converts it to a monthly decimal.
• Assuming every mortgage is fixed-rate: Adjustable rates, introductory periods, interest-only periods, and changing payment structures are not represented by this fixed-payment formula.
• Expecting the exact lender schedule: Payment dates, daily accrual, rounding practices, fees financed into the balance, and payment changes can affect actual figures.
• Ignoring extra payments: Extra principal payments can alter a payoff timeline and interest total, but they are not included here. The displayed estimate assumes only the scheduled level payment.

Use the calculation to understand the relationship among principal, APR, term, payment, and total interest. To build a full schedule, calculate each month’s interest from the starting balance, subtract it from the payment to find principal paid, and subtract that principal from the balance before moving to the next month. A lender’s loan disclosure or servicing schedule supplies transaction-specific figures.

Frequently Asked Questions

What is an amortization schedule for a home loan?
An amortization schedule is a table showing how each scheduled payment is divided between interest and principal, along with the remaining balance after payment.

Does a mortgage payment include taxes and insurance?
This calculator does not include property taxes, homeowners insurance, mortgage insurance, escrow, or fees. It estimates only principal and interest.

Why does more of an early payment go to interest?
Interest for a period is based on the balance at the start of that period. The balance is largest near the beginning of repayment, so the interest share of a level payment is usually larger then.

Can I use this for an adjustable-rate mortgage?
Only for a period where the entered rate is applicable and payments follow the fixed-rate assumptions. The calculator does not model future rate resets or resulting payment changes.

How do extra payments affect an amortization schedule?
Extra amounts applied to principal can reduce the balance faster and change subsequent interest. This calculator has no extra-payment input, so its total assumes scheduled payments only.

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

Related

• Amortization Formula With Extra Payments: How It Works
• Amortization Calculator With Down Payment
• Amortization Calculator With Known Payment

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