Put this calculator on your site. Free, forever.

It answers the question people actually ask before they buy an air purifier — what clean-air delivery rate does my room need, and what will it cost to run? It also tells them when one unit isn't enough, which most retailers won't.

What it looks like

The code

Paste this wherever you want it to appear. That's the whole installation.

<iframe src="https://theairmath.pages.dev/widget.html"
        width="100%" height="720" style="border:0;border-radius:16px"
        loading="lazy" title="Air purifier size calculator"></iframe>

Works in WordPress (Custom HTML block), Ghost, Squarespace, Webflow, Notion embeds and plain HTML.

Optional: make it resize itself

The widget posts its height to the parent page. If you can add a script tag, this removes any empty space or inner scrollbar:

<script>
window.addEventListener('message', function (e) {
  if (e.data && e.data.airmathHeight) {
    var f = document.querySelector('iframe[src*="theairmath"]');
    if (f) f.style.height = e.data.airmathHeight + 'px';
  }
});
</script>

The terms, in plain language

• It's free and it stays free. No account, no key, no usage limit.
• No tracking of your readers. The widget sets no cookies and sends no analytics. It is a calculator, not a pixel.
• Keep the attribution line. That link back to The Air Math is how this pays for itself.
• The product button is an affiliate link. We say so on the widget and we're saying it here. If a reader buys, we may earn a commission — you don't, and nothing changes for them.
• Don't misrepresent it. Don't present it as your own tool or edit the numbers.

Why the numbers are trustworthy

The formula is the standard one: required CADR equals room volume times target air changes per hour, divided by 60. Coverage figures assume maximum fan speed in a closed single room, which is how AHAM rates them and how the EPA recommends sizing. Unit specifications come from published manufacturer data.

We have not physically tested these units and we say so on every page. What we do instead is show the working, so anyone can check it — including you, before you put it in front of your readers.

If you spot an error, tell us and we'll change it rather than quietly leave it.