Free Calculator Widgets for Your Website

How do I add a calculator to my website?

Three steps, and none of them involve installing anything. Choose the calculator you want in the builder above, press Copy code, then paste the snippet into your page wherever the calculator should appear. Because the widget is an ordinary iframe, it works in every content management system that allows an HTML or embed block — WordPress, Squarespace, Wix, Shopify, Webflow, Ghost, HubSpot, Notion sites and hand-written HTML all handle it the same way.

There is nothing to configure afterwards. The snippet carries its settings in the URL, so if you later want a dark version or a different currency you simply come back, rebuild the snippet and swap it. Nothing is stored on our side, and there is no account to manage or key to rotate.

What does the snippet actually contain?

Two things, and it is worth knowing why both are there. The first is the iframe that renders the calculator. The second is a short attribution line underneath the iframe, in your page's own HTML.

That placement is deliberate rather than decorative. Anything inside an iframe belongs to the framed document, not to your page — search engines read it as a separate document, and so do most accessibility tools and readability checkers. Keeping the credit line in your own markup is the only way it is visible to a reader who is skimming, to a screen reader moving through your page, and to a search engine building context for the section. It is one line, it is unstyled so it inherits your typography, and you can move it above the calculator if you prefer.

Will it slow my page down?

Barely. The widget is a single self-contained HTML file: the CSS and JavaScript are inline, so it makes no extra requests once the frame loads. It pulls in no web fonts, no images, no framework, no analytics and no advertising. The snippet also sets loading="lazy", so a widget placed far down a long article is not fetched until the visitor scrolls near it, and it costs nothing on first paint.

It sets no cookies and stores nothing in the visitor's browser, so it does not add a consent obligation to your site. The arithmetic runs locally inside the frame and the numbers your visitor types are never transmitted anywhere — not to us, and not to anyone else.

Fixed height or auto-height?

By default the snippet uses a fixed height chosen to fit that widget's longest result, which is the most robust option because it involves no scripting on your page at all. If you would rather the frame track its content exactly, tick the auto-height box and the snippet gains a short script that listens for the height the widget reports and applies it.

That script is written defensively: it ignores any message that did not come from calccopilot.com, checks the shape of the message before using it, and only ever sets a pixel height. The widget itself registers no message listener at all, so there is no channel for a page to push data into it. If you are unsure, leave the box unticked — the fixed height works everywhere.

Customisation reference

Every option is a plain URL parameter, so you can also hand-edit the snippet instead of using the builder.

Anything outside these lists is ignored and the widget falls back to its default, so a typo can never break the page it is embedded in.

Terms of use

You may use these widgets on any number of pages, on commercial sites as well as personal ones, free of charge and for as long as you like. We ask one thing in return: keep the attribution line that comes with the snippet, because word of mouth is how a small independent site gets found.

Nothing in the widget checks whether the credit is present, and it will keep working if you remove it — we would simply rather you didn't. If your editorial policy requires outbound links to be marked, tick the nofollow box in the builder instead of deleting the line; the credit still reads the same to a human. Please don't modify the widget to misrepresent where the numbers come from, and remember that the calculators are estimates for general guidance, not financial advice.

Also useful: the full Mortgage Calculator adds property tax, insurance, PMI, extra payments and a full amortisation schedule, and the Compound Interest Calculator adds withdrawals, contribution growth and an effective-APY breakdown.

Built and tested by CalcCopilot's founder, background in engineering and mathematics. Last updated September 2026.