Loan Amortization Calculator — a tool that computes monthly loan payments, total interest, an amortization schedule, and displays interactive charts of balance and payment breakdown using Plotly.js.

How this calculator helps you

This calculator quickly calculates monthly payments from principal, interest rate, and term. It produces a full amortization schedule, shows how much interest you will pay over time, and gives interactive visualizations so you can explore principal vs interest components. It’s designed to be embedded inside a WordPress custom HTML block and sized to fit between two sidebars.

What the tool includes

The tool includes:

• Inputs for loan amount, annual interest rate, loan term (years), and extra monthly payment.
• Instant numerical results: monthly payment, total payment, and total interest.
• An amortization table that lists each payment, principal and interest components, and remaining balance.
• Two Plotly charts: a line chart of remaining balance over time, and a stacked area chart showing principal vs interest paid across the loan term.
• A responsive layout that adapts to narrow screens and uses a white background for clarity and print-friendliness.

How to use it — step by step

1. Paste the provided HTML/JavaScript code into a WordPress Custom HTML / Code block in the page where you want the calculator to appear.
2. Enter your loan amount (principal), the annual interest rate (for example 4.25), and the duration of the loan in years (for example 30).
3. Optionally add an extra monthly payment to see how additional payments shorten the loan and reduce interest.
4. Click Calculate. Results appear instantly and charts update in place; you can hover to inspect values and zoom the charts.

Accessibility and responsiveness

The inputs are standard HTML controls with visible labels and keyboard support. Layout is responsive: on small screens the control panel stacks above charts and table. The visual contrast uses black text on white background for readability. All interactive charts provided by Plotly are keyboard- and screen-reader-friendly to the extent Plotly supports standard accessibility features; consider adding aria-labels or bespoke summaries for full conformance.

Why plot with Plotly.js?

Plotly gives interactive charts with hover, pan, zoom and downloadable PNGs built-in. That interactivity is useful when exploring amortization where fine-grained differences matter. Plotly also integrates easily into a single static HTML file, which makes this calculator portable and quick to install on WordPress.

Quick troubleshooting

If charts fail to render, check the browser console for network errors loading Plotly. Also confirm the custom HTML block allows inline scripts — some WordPress setups strip scripts; in that case use a plugin that allows safe inline JS or enqueue the script via your theme or child theme. If numbers look wrong, verify interest is entered as an annual percentage, not a decimal (for example 5 for 5% not 0.05).

Advanced use cases and customization

The calculator can be extended for different financial analyses: add inputs for APR vs nominal rate, include origination fees, model balloon payments, or adapt it for investment projections by switching rate interpretation. Developers can wire the calculator to server-side services to persist user scenarios for later retrieval or to compare lender quotes. For teams that need branded visuals, update the CSS variables at the top: swap fonts, button shapes, and chart color palettes. You can also add a CSV export button to download the amortization schedule for use in Excel or Google Sheets. When integrating into a WordPress site, test inside the exact page template used for end users: some page builders wrap content in additional containers that affect width, so adjust max-width accordingly. Finally, consider adding small explanatory tooltips next to each input to improve conversions and user trust. These incremental enhancements improve accuracy and user experience and make the tool more trustworthy for visitors and stakeholders. Test on staging first. regularly.

Disclaimer

This calculator provides estimates only and is not financial advice. Results depend on the inputs provided; always verify calculations with a qualified financial advisor or loan officer before making financial decisions. The author and provider are not responsible for losses arising from use of this tool.

FAQ

Q: Can I change currency or display decimals?
A: Yes — the code formats currency using the browser locale. You can adjust formatting to a specific currency symbol in the script.

Q: Is user data sent anywhere?
A: No — all calculations run in the browser; nothing is transmitted to external servers by the calculator.

Q: Can I export the amortization table?
A: You can copy the table or use browser print/save as PDF. The code could be extended to export CSV if desired.

Q: Will this work on mobile?
A: Yes — the layout is responsive and the charts reflow for narrow viewports.

Q: Can I customize the colors and fonts?
A: Yes — change the CSS variables at the top of the snippet or wrap the calculator in your theme styles.