Mortgage Calculator

Calculate monthly mortgage payments, total interest, and amortization schedules from home price, down payment, interest rate, and loan term.

2. Core Features

2.1 Loan Amount Input

Supports users to input any loan principal amount.

Multi-Country Currency Adaptation: The system automatically displays the corresponding currency symbol based on different countries (such as $, €, £, ¥, etc.), no manual selection required.

2.2 Interest Rate and Term Settings

• Annual Interest Rate: Customizable input accurate to two decimal places (e.g., 6.50%).
• Loan Term: Supports 1 to 50 years of integer options, covering most mortgage products.

2.3 Calculation Results Display

After clicking the “Calculate” button, the system immediately displays:

• Monthly Payment: Precisely calculated based on the equal principal and interest formula.
• Total Interest: Total interest payable over the entire loan cycle.
• Total Repayment: Principal + Total Interest.

2.4 Amortization Schedule

Displays the first 360 periods (30 years) of monthly repayment details, including:

• Period number
• Monthly principal repayment
• Monthly interest repayment
• Remaining loan balance

Helps users clearly understand the composition changes of principal and interest in each payment.

2.5 Reset Function

Click the “Reset” button to clear all input fields with one click and quickly start a new calculation.

3. How to Use

1. Enter the total loan amount in the “Loan Amount” field.
2. Enter the annual interest rate provided by the bank in the “Annual Interest Rate” field.
3. Select or enter the number of years in the “Loan Term” field.
4. Click the “Calculate” button.
5. View the results area above: monthly payment, total interest, total repayment amount.
6. Scroll down to view the detailed amortization schedule.
7. To recalculate, click the “Reset” button.

4. Typical Use Cases

Scenario	Description
Home Purchase Preparation	Input different house prices, down payment ratios, and interest rates to estimate monthly payment burden.
Loan Plan Comparison	Compare monthly payments and total interest differences between different banks or loan products.
Repayment Planning	View the amortization schedule to understand the characteristics of high interest proportion in early periods, and develop early repayment strategies.
Family Budget Evaluation	Evaluate the impact of mortgage on monthly cash flow and long-term family finances.

5. Notes

• Calculation results are for reference only: Actual monthly payments may vary slightly due to bank fees, insurance, appraisal fees, and interest rate fluctuations.
• Repayment method limitation: This tool uses the equal principal and interest (fixed monthly payment) calculation method, which is the most common mortgage repayment method. For equal principal repayment, please use other specialized tools.
• Amortization schedule range: Only the first 360 periods (30 years) are displayed. For a complete term plan, please obtain it from your loan bank.
• Please consult professionals before major decisions: It is recommended to combine professional financial advisor opinions before signing a loan contract.

6. Technical Description and Data Security

• Calculation formula: Monthly Payment = Principal × [Monthly Rate × (1+Monthly Rate)^Months] / [(1+Monthly Rate)^Months - 1]
• Data privacy: All calculations are completed locally in the user’s browser, and no input data will be uploaded to the server, ensuring personal information security.

Last verified: 2026-04-06

Source: Built based on open source project jekhokie/mortgage-calculator.