Free calculator widgets for your website

Yes. There is no charge, no account, no API key and no usage limit. The one thing we ask is that you keep the credit link that comes with the code — that link is what pays for the widget being free.

The widget is an iframe marked loading="lazy", so the browser does not fetch it until the reader scrolls near it, and it never blocks your own page from rendering. The optional resize script is about a kilobyte.

Yes, and that is the main reason to embed rather than copy. Tax tables, contribution limits and exchange rates are maintained here, so a widget you pasted last year is running this year's numbers without you touching it.

Yes. Any input can go in the URL, so a mortgage widget on a page about first-time buyers can open at the price and rate you are writing about. Set the calculator up on its own page, then use the Embed button — the code it gives you carries whatever you entered.

Then you would see an empty frame, which is why the credit link sits outside it in your own HTML rather than inside the frame — your readers still get a working link to the calculator either way.

It sizes itself to the space you give it, and you can pin it to light or dark rather than following the reader's own setting — useful if your site is always one or the other. Fonts and colours beyond that are not configurable.

On a platform that speaks oEmbed, yes — paste the calculator's URL on its own line and it becomes the widget, credit and all. Everywhere else, the three lines are the way, and they work on any site that accepts HTML.

Please keep the credit line the code includes. It is a normal editorial link to the source of the widget, so please do not mark it nofollow. Beyond that there is no attribution requirement and no licence to sign.