Mortgage calculator definition: An interactive web tool that computes monthly (or periodic) payments, total interest, total paid, and an amortization schedule with interactive Plotly.js visualizations from loan amount, interest rate, term, and payment frequency.

How to use the mortgage calculator

This mortgage calculator is built to drop into a WordPress Custom HTML block or a theme template and fits neatly between two sidebars by using a responsive container with a maximum width suitable for most WordPress content areas. It offers clear inputs for loan amount, annual interest rate, loan term, and payment frequency; it computes periodic payments, total cost, and total interest; and it presents an interactive Plotly.js chart and a compact amortization table. The interface has a white background and mobile-responsive layout to match typical site styling.

What the calculator does and why it matters

When planning to buy, refinance, or compare mortgage options, you need a quick and reliable way to see monthly payment estimates and total borrowing costs. This calculator performs standard fixed-rate amortization calculations in the browser (client-side), so it’s fast, private, and does not require a server. The interactive chart lets you visually inspect remaining balance over time and a stacked principal/interest breakdown for each payment period. Visualizations increase engagement and help users understand how early payments disproportionately service interest while later payments build equity.

Quick start: entering values

1. Loan amount — enter the principal you plan to borrow (for example, 300000).
2. Annual interest rate — enter the yearly rate as a percentage (for example, 3.75).
3. Term — enter the mortgage term in years (common choices are 15 or 30).
4. Payments per year — choose monthly (12), biweekly (26), or weekly (52) to see how frequency affects payoff and interest.
5. Click Calculate — the tool shows per-period payment, total paid across the loan life, and total interest.

Reading the outputs

• Periodic payment: the amount you pay each payment period (monthly, weekly, etc.).
• Total paid: sum of all payments over the loan term.
• Total interest: the cumulative interest portion over the life of the loan.
• Amortization table: a row-per-payment breakdown of principal, interest, and remaining balance; CSV export is available for offline review.
• Charts: hover or zoom on the Plotly chart to inspect specific payments and balances.

Example walkthrough

Try this example: Loan amount $300,000, annual rate 4.0%, term 30 years, monthly payments. Click Calculate to see a periodic payment (around $1,432), total paid (about $515,610), and total interest (approximately $215,610). The chart highlights interest-heavy early years and growing principal later. Changing the rate or shortening the term instantly shows the payment and interest impact.

Embedding and WordPress compatibility

The code is a single HTML file using Plotly.js from a CDN and standard CSS. It’s designed to be pasted into a WordPress Custom HTML block or included in a child-theme template. The container uses max-width: 760px and width: 100% so it fits common content columns and will not overflow sidebars. If your theme limits content width further, adjust the max-width in the CSS.

Plotly visuals and interactivity

Plotly.js powers an interactive line (remaining balance) and stacked bar (principal vs interest) chart. Users can:

• Hover for precise values per payment.
• Zoom into the early or late years.
• Toggle series visibility to focus on a single series.
  This interactivity keeps users engaged and improves the page’s dwell time.

Accessibility and usability

The calculator uses labeled inputs and keyboard-focusable controls. Numeric inputs validate values (e.g., not leaving the loan amount blank). The layout stacks vertically on small screens for accessible mobile use. Tooltips, clear labels, and an export feature ensure usability for various audiences.

Troubleshooting and support

If the chart doesn’t render, confirm your WordPress installation allows external scripts (Plotly CDN). For JavaScript errors, check the browser console (Developer Tools → Console). If results seem off, ensure you entered percentages as whole numbers (enter 3.75 for 3.75%). For custom styling, localization, currency formats, or to connect live rate APIs, consult a developer.

Security, privacy, and limitations

All calculations run in the browser; no user inputs are sent to third parties by the core tool. If you integrate analytics or server-side storage, disclose that in your privacy policy. The calculator assumes fixed-rate loans and excludes taxes, insurance, closing costs, PMI, or lender fees — include those externally for a full cost picture.

Disclaimer

This mortgage calculator provides estimates for informational purposes only and is not financial, legal, or tax advice. Use the results as a guide and consult a licensed lender, financial advisor, or tax professional before making decisions.

Frequently Asked Questions (FAQ)

What inputs are required?

Loan amount, annual interest rate, term in years, and payment frequency (monthly/biweekly/weekly). You can optionally add extra payments if the code is extended.

Are results exact?

For fixed-rate mortgages the math is standard and accurate for amortization schedules. Results are estimates and don’t include fees, taxes, or insurance.

Can I export the amortization schedule?

Yes — the tool includes a CSV export button to download the full schedule.

Will it work in any WordPress theme?

Yes — because it uses standard HTML/CSS/Plotly CDN scripts. If your theme restricts external scripts or uses CSP rules, allow Plotly or host it locally.

Can I customize appearance or currency?

Yes — the code is modular. You can change CSS, adjust currency formatting in JavaScript, or adapt chart colors.

Who should use this tool?

Homebuyers, brokers, real estate professionals, and anyone comparing mortgage scenarios.

Enjoy smarter borrowing decisions.