WordPress plugin · demo project, fictional brand

ROI calculator with lead capture

A savings and payback calculator for an LED lighting retrofit, added to any page with a shortcode.

The problem

Visitors want a number for their own case before they talk to sales. The calculator gives it instantly and turns the interest into a lead.

Live results while typing: yearly saving, payback, net after five years, return, energy and CO2 saved, with a five-year chart.
Input checks with one plain message on the field that needs fixing.
"Email me this estimate": the visitor gets the estimate by email, the owner gets the lead, and the server recalculates every number.
Settings page for default values, currency and the lead email; colours follow the theme.

The PHP formula (PHP 8.3 and 7.4) and the JavaScript formula return identical results on the same hand-calculated cases.
5 of 5 end-to-end tests on a fresh WordPress: default numbers match the hand calculation, live update and error state, lead saved with server numbers and both emails sent, spam trap stores nothing, phone layout.
Testing caught four real bugs before delivery, including a form that could not send on block themes.

Built with: WordPress plugin (PHP 7.4+), REST API, vanilla JavaScript, SVG chart

Need something like this for your business?Hire me on Upwork