Numerly

Embed any Numerly tool

One line of HTML. 97+ tools. Free for any site, big or small.

One line

Copy an iframe snippet. Paste anywhere HTML works. The tool loads in your reader's browser, runs locally, and renders instantly.

Free forever

No API key, no monthly limit, no tracking on your visitors. The math runs on the user's device — we don't even know they used it.

No upkeep

When we ship a fix or feature, every embed gets it automatically. No SDK to update, no version bumps.

How to embed

  1. 01

    Open any tool page

    Browse the catalog or use the search palette (⌘K). Every page has an Embed button near the bottom.

  2. 02

    Pick a size and copy the code

    Three size presets, three code formats — HTML, Markdown, WordPress. Hit Copy.

  3. 03

    Paste into your post

    Any CMS that accepts iframes (Ghost, Webflow, WordPress Custom HTML, Notion via embed, Squarespace, Wix). The tool appears inline and works immediately.

What the code looks like

<iframe src="https://numerly.io/embed/converters/length/kg-to-lbs"
width="100%" height="480" frameborder="0"
loading="lazy"
title="Kilograms to Pounds by Numerly"></iframe>

That's it. The embed page renders the same widget you see on numerly.io, minus the site chrome, plus a small “Powered by Numerly →” link at the footer. (Yes, that link is required — it's the only thing we ask in return.)

Tools to embed

The most popular ones — but every Numerly tool has its own embed.

Converters

Calculators

Generators

Decision tools

Who embeds these tools

  • Cooking blogs

    Embed a cups-to-grams or oz-to-ml converter inside a recipe so readers can switch units without leaving the page.

  • Fitness writers

    Drop a TDEE, BMR, or one-rep-max calculator beside a workout plan. Readers compute their numbers and stay engaged.

  • DIY and hardware sites

    Add mm-to-inches or feet-to-meters converters next to a build guide. No app needed, no page jump.

  • Student / study resources

    Embed the GPA calculator or unit converters into a course page. Free, no sign-in, friendly to younger audiences.

  • Newsletters and Substacks

    Embed the random quote or yes-or-no wheel for a weekly interactive moment. Keeps readers clicking back.

The deal

  • Free, no API key, no rate limit. Use as many embeds as you like.
  • Keep the “Powered by Numerly” link. It's baked into the embed footer. That's how we earn our keep.
  • No tracking on your readers. We use Vercel Analytics for aggregate counts only — no cookies, no fingerprinting.
  • No commitment. Remove the embed any time. Nothing to cancel, nothing to negotiate.

Questions?

Email hi@numerly.io. We answer within a few days.