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MortgageCalcPro

Mortgage Amortization Schedule Calculator

Enter your loan details below to generate a complete month-by-month amortization schedule. Download it as a CSV for Excel or Google Sheets.

Loan Details

Total amount borrowed

Fixed annual rate

Total repayment period

How Mortgage Amortization Works

When you take out a fixed-rate mortgage, each monthly payment is split into two parts: interest charged on the outstanding balance and principal that reduces the loan. Early in the term, interest dominates each payment. As the balance shrinks, a larger share goes toward principal — this shift is called amortization.

The monthly payment is derived from the standard annuity formula:

M = P × [r(1 + r)n] / [(1 + r)n − 1]

Where P = principal, r = monthly interest rate, n = total number of payments

Our calculator applies this formula and generates the complete schedule showing every payment's breakdown, making it easy to see exactly how much interest you'll pay over the life of the loan.

Frequently Asked Questions

How is a mortgage amortization schedule calculated?

A mortgage amortization schedule is calculated using the standard annuity formula. Your fixed monthly payment is split between interest (calculated on the remaining balance) and principal repayment. Over time, the interest portion decreases and the principal portion increases, until the loan is fully paid off.

Can I download my amortization schedule?

Yes! After calculating your schedule, click the "Download CSV" button. The file opens directly in Microsoft Excel, Google Sheets, or any spreadsheet application. It includes the payment number, monthly payment, principal, interest, and remaining balance for every month.

Does this calculator support adjustable-rate mortgages (ARM)?

This calculator is designed for fixed-rate mortgages. For adjustable-rate mortgages, you would need to recalculate each time the rate changes. You can use this tool to model individual fixed periods of an ARM.

Is my financial data stored or sent to a server?

No. All calculations run entirely in your browser using JavaScript. No data is transmitted to any server, stored in cookies, or shared with third parties. Your financial information stays on your device.