How to add a calculator to a plain HTML website
Every Plainso tool is a single iframe, so if you can edit HTML, you can add a calculator. Paste one line into your page and it runs — no build step, no JavaScript, no dependencies to install.
Step by step
Copy the embed code
Open the tool you want and copy the one-line iframe snippet from its embed section.
Open your HTML file or editor
Go to the point in your page where the calculator should appear — in the body, inside the section you want it in.
Paste the iframe
Paste the snippet exactly as copied. The iframe tag is self-contained and needs nothing else on the page.
Save and reload
Save the file (or publish the page) and reload it. The calculator renders in place.
What it looks like embedded
Good tools to embed on Plain HTML
Good to know
- The iframe is responsive — set width="100%" and the calculator fills its container on mobile and desktop.
- Any CMS with an HTML or code mode (Ghost, Hugo, Jekyll, Astro, Carrd, Webflow, Notion exports) accepts the same snippet.
- No build step or bundler is involved: the snippet is plain HTML, so it works in a hand-written .html file too.
Frequently asked questions
Quick answers before you start.
Can I embed a calculator without JavaScript?
Yes. The calculator is an iframe, so you paste an HTML tag and nothing else. There's no script to add, no library to load, and no code to maintain.
Does the calculator resize on mobile?
Yes, if you set the iframe's width to 100%. The calculator inside is responsive and reflows to fit narrow screens automatically.
Can I add more than one calculator to a page?
Yes. Each tool has its own snippet, and you can place as many as you like on a page. They're independent iframes, so they don't interfere with each other.