Put a free calculator on your site
Every Calcistry tool is free to embed on your blog, newsletter or client site — no sign-up, no fees, ever. Copy the snippet, paste it into your page's HTML, and you're done. The calculator resizes itself and always works. We only ask that you keep the small credit link.
How to embed a calculator
- Pick a calculator above and click Copy code.
- Paste it into your page where you want the tool to appear — in WordPress use a Custom HTML block; in Webflow/Squarespace use an Embed / Code block.
- Publish. The calculator loads instantly and auto-sizes to fit. Nothing to maintain — updates happen on our side.
Rules (they're simple)
- Free forever for any site, including commercial ones.
- Keep the credit link to Calcistry that comes with the snippet — that's the only condition.
- Don't modify the calculator's logic or misrepresent the results as your own tool.
Why we give these away
A calculator is the part of a finance article that readers actually use. Someone reading about mortgage recasting does not want a definition — they want to know what happens to their payment if they put down £20,000. Writing that tool yourself means specifying the amortisation maths, testing the edge cases, making it work on a phone, and then maintaining it forever. Most writers reasonably decide it is not worth it, and the article ends up worse for it.
We already built and tested these, so the marginal cost of letting you use one is zero. In return the snippet carries a small credit link back to Calcistry. That is the whole arrangement: you get a working tool without maintaining it, we get a link. No sign-up, no account, no tracking pixel, no price that appears later.
What the embed actually does on your page
The snippet is a plain <iframe> pointing at the calculator page, plus a few lines that let it report its height back to the parent so it resizes instead of scrolling inside a fixed box. There is no JavaScript library to install and nothing that touches the rest of your page.
Some specifics worth knowing before you paste it in:
- Performance. The frame loads lazily, so it does not block your page rendering and does not count against your own largest-contentful-paint measurement.
- Privacy. The embedded calculator runs entirely in the visitor’s browser. Numbers typed into it are never sent to us, which also means we cannot see them, log them, or lose them.
- Mobile. The layout collapses to a single column below roughly 700px, so it behaves on a phone without any work from you.
- SEO. Content inside an iframe is not indexed as part of your page. Treat the calculator as a tool for your readers, not as a substitute for the words around it — you still want your own explanation on the page.
Where an embedded calculator earns its place
The tools land best when they sit next to a decision the reader is already trying to make. A few pairings that work in practice:
A mortgage overpayment post pairs naturally with the recast calculator, because the interesting question is not whether overpaying helps but whether recasting or shortening the term helps more.
A FIRE or early-retirement piece benefits from Coast FIRE, since the number that changes minds is the age at which you could stop contributing entirely and still retire on time.
A debt payoff guide is where the snowball tool belongs — readers arrive with several balances and no clear idea of the order, and a table of their own debts answers it faster than any amount of prose.
A dividend investing article is improved by yield on cost, mostly because it exposes how slowly the headline figure moves in the early years, which is the opposite of what most readers expect.
Frequently asked, in more detail
Will this ever start costing money?
No. There is no account behind the embed and no billing system to switch on. If a calculator is ever retired, the page it points at will redirect rather than break, so an old embed keeps working.
Can I restyle it to match my site?
You can change the width and the surrounding spacing freely. The interior styling stays as-is, which is deliberate — it keeps every embed consistent and means we can fix bugs without breaking anyone’s customisation.
Do I have to disclose that it is a third-party tool?
The credit link that ships with the snippet covers attribution. If you write about regulated financial topics, your own jurisdiction may require an educational-estimate disclaimer as well — the calculators show one, but check what applies to you.
Can you build a calculator I need but you do not have?
Ask. Requests that come from people actually publishing on the topic are the most useful signal we get about what to build next.
Calculators are educational estimates, not financial advice. Questions or want a tool we don't have yet? Get in touch.