Embed a unit converter

Add a free converter to any site with one async script or a lazy iframe. No sign-up. Host pages stay fast if you keep the snippet async and sized.

Snippets below are prefilled for foot to meter (ft-to-m). Canonical URL stays /embed.

How to embed

Copy a snippet. Copy the recommended async JavaScript widget or the lazy iframe. Add ?pair= on this page to prefill a published converter such as psi-to-kpa or m-to-ft.
Paste it on your page. Place the snippet where the calculator should appear. Keep the script async, or add loading="lazy" on the iframe, so the host page stays fast.
Keep the Powered by credit. Leave the visible Powered by AllUnitConversions link in place. It deep-links with ?ref=embed for analytics and canonicalizes to the clean URL.

Recommended: async JavaScript widget

The script is a small static file. Use async so it never blocks your page. Place the div where the calculator should appear. Optional attributes: data-pair, data-category, data-from, data-to, data-value.

<!-- Powered by AllUnitConversions https://allunitconversions.com/ft-to-m?ref=embed -->
<div data-allunitconversions-widget data-mode="popular" data-pair="ft-to-m" data-value="10"></div>
<script src="https://allunitconversions.com/_assets/converter-widget.js" async></script>

Alternative: lazy iframe

Point the iframe at /widget. That route is a static document (no site chrome) so it does not pull this app's React bundle into your page. Add loading="lazy" and a ?pair= deep-link when you want a preset.

<iframe
  src="https://allunitconversions.com/widget?pair=ft-to-m"
  title="foot to meter converter"
  width="320"
  height="240"
  loading="lazy"
  referrerpolicy="strict-origin-when-cross-origin"
  style="border:0;border-radius:8px;max-width:100%;"
></iframe>
<!-- Powered by AllUnitConversions https://allunitconversions.com/ft-to-m?ref=embed -->

Live examples

Length · meters to feet

Async JS widget with data-pair="m-to-ft".

Volume · liters to gallons

Second async instance on the same page.

foot to meter

Lazy iframe of /widget?pair=ft-to-m (compact 320×240).

Sizing

Preset	Width	Height	Use
Compact	320px	240px	Sidebar, cards, and docs asides.
Default	360px	280px	Article body or classroom page.
Wide	420px	320px	Give the category widget more room.

For a responsive iframe, wrap it in a container with max-width: 100% and keep the iframe width at 100% of that container. The JS widget maxes out at 420px and shrinks with the host column.

Allowed domains

Any public HTTPS site may embed. /widget is framed with Content-Security-Policy: frame-ancestors * and does not send X-Frame-Options: SAMEORIGIN. Other routes stay clickjack-protected.
Your host page must allow our origin. For the async widget, add https://allunitconversions.com to script-src. For the iframe, allow it in frame-src.
We do not currently restrict embeds to an allowlist. If you need a private allowlist later, contact us before going live.

Referral links and canonicals

Every embed shows a visible Powered by AllUnitConversions link, and snippets include the same credit as an HTML comment. The link deep-links to the matching published pair when one exists (otherwise the category hub or homepage) with ?ref=embed.

?ref=embed is ignored for on-page UX. Calculators, copy, and navigation do not change.
Analytics can read the query on first load, then the client strips it (same as UTM parameters) so the address bar returns to the clean URL.
Page metadata always canonicalizes to the clean path. Example: https://allunitconversions.com/m-to-ft?ref=embed canonicalizes to https://allunitconversions.com/m-to-ft. Referral URLs are not added to sitemaps, so they are not indexable soft duplicates.
/widget itself is noindex and canonicalizes to https://allunitconversions.com/widget without query strings.
This docs page canonicalizes to https://allunitconversions.com/embed even when opened with ?pair= prefill.

The category widget (length, pressure, force, power, volume) also has a dedicated landing page at /embed/unit-converter-widget. Prefer this docs page when you need sizing, domain, or referral details.