How to embed a calculator on your website

Add any of our calculators to your site with one line of code — free, no API key, no sign-up.

Why embed a calculator?

An embedded calculator keeps visitors on your page longer and adds genuine utility — a tip calculator on a restaurant blog, a mortgage calculator on a real-estate listing, a BMI tool on a fitness site. Because each one is privacy-first and runs entirely in the visitor's browser, you get the usefulness without collecting anyone's data or slowing your page down.

How to embed in three steps

Open the embed gallery and find the calculator you want.
Click Copy embed code to copy its one-line iframe snippet.
Paste the snippet into a Custom HTML / Embed block where you want it to appear.

Example snippet

Every embed looks like this — just swap the calculator name in the URL:

<iframe src="https://numvella.com/embed/percentage-calculator"
  width="100%" height="460"
  style="border:1px solid #e2e8f0;border-radius:12px"
  title="Percentage Calculator — Numvella" loading="lazy"></iframe>

Sizing and customization

The snippet is responsive by default (width="100%"), so it fills its container. Adjust height if a particular calculator needs more or less room, and keep loading="lazy" so the widget only loads when a visitor scrolls to it. The rounded border is optional — edit or remove the inline style to match your design.

Platform notes

WordPress: add a Custom HTML block and paste the snippet (avoid the visual editor, which can strip iframes).
Squarespace / Wix / Webflow: use an Embed or Custom HTML element.
Ghost / Notion / plain HTML: paste directly into an HTML block or your page source.

Licensing & attribution

Embeds are free for any site, including commercial ones. Each widget includes a small "Powered by Numvella" link back to the full calculator — please keep it. That link is the only thing we ask in return for free, unlimited embedding.

Frequently asked questions

Is embedding a calculator free?

Yes — every calculator is free to embed, forever, with no API key, account, or usage limits. The only ask is that you keep the small “Powered by Numvella” link in the widget.

Will an embed slow down my site?

No. The calculator loads in an isolated iframe, so it never blocks your page, and all computation runs in the visitor's browser. Add loading="lazy" (as in the snippet) so it only loads when scrolled into view.

Can I use these embeds on WordPress, Squarespace, or Wix?

Yes. Paste the iframe snippet into a “Custom HTML” / “Embed” block on any platform that allows HTML. On WordPress, use a Custom HTML block (not the visual editor).

Do the embeds collect my visitors' data?

No. The calculators are privacy-first: the numbers your visitors enter are processed locally in their browser and are never sent to a server.

Ready to add one? Browse the embed gallery →