Free Embeddable Weight Loss Calculator
Add an interactive Monte Carlo weight loss timeline calculator to your website or blog. No account. No API key. No cost. Two-line snippet, works on most website platforms.
Copy the two lines of code below and paste them into your article or page. The widget will render automatically, complete with all 7 inputs and 3 outcome cards. Units auto-detect from the reader's timezone — or you can pin them with data-units="imperial". One <script> tag per page is enough.
Runs 5,000 Monte Carlo simulations using the Mifflin-St Jeor BMR equation with weekly metabolic adaptation. Returns best case (10%), most likely (50%), and realistic (75%) completion weeks — not a single fake date.
Works on most website platforms
Frequently asked questions
Yes, completely free. No account, no API key, no usage limits. The simulation runs entirely in your reader's browser — their data never leaves their device.
No. The script is under 15 KB, loads asynchronously, and has no external dependencies. It won't affect your Core Web Vitals. Each simulation (5,000 runs) typically completes in a fraction of a second on modern devices.
No. The widget runs inside a Shadow DOM, which fully isolates it from your page's styles. Your CSS can't break the widget, and the widget can't override your CSS.
Yes. Paste the two lines into the HTML block of any post or page. Works with the classic editor and the block editor (Gutenberg). No plugin needed.
Units auto-detect from the reader's IANA timezone — US and Hawaii visitors see lbs/in, everyone else sees kg/cm. You can override this with data-units="imperial" or data-units="metric" on the div.
The widget ships with a light theme (default) and a dark theme via data-theme="dark". Custom brand colours are not currently supported, but the neutral design fits most sites without adjustment.
No. The calculator runs entirely in the browser. No login, no cookies, no data sent to any server.
It uses the Mifflin-St Jeor BMR equation — the most widely validated formula in clinical use — recalculated each simulated week as weight changes. It does not account for activity level, resistance training, or medical conditions. It is a statistical model for planning, not a medical prediction.
Yes. A small "Powered by HonestSlim" link appears below the calculator. This helps us keep the widget free for everyone — no account, no API key, no cost to you or your readers.