Put the numbers on your own site
825 pages of arithmetic, and three ways to use them somewhere else. All of it is free, none of it needs an account, and nothing here tracks the people who use it — which is also why there is no consent banner to inherit.
Embed a calculator
An iframe that opens on the numbers you choose and recomputes against this site.
Free for commercial use. The one condition is the credit link inside the widget. It sets no cookies, sends nothing to your visitors’ browsers beyond the calculator itself, and cannot read anything on your page.
Build an embedCall the JSON endpoint
GET /api/calc/{slug} returns the value, every intermediate step, and the sources.
No key and no sign-up. Values may be passed as strings carrying units — "5ft 11in", "3/8", "165 lbs" — so you can hand it what a user typed rather than parsing first. Cached at the edge, so a busy page is not a busy origin.
Read the APIGive an agent the tools
Every calculator is exposed as an MCP tool over JSON-RPC at /api/mcp.
An assistant that can call these does arithmetic it cannot get wrong, and gets back the derivation with the answer so it can show its work. This is the surface almost nobody in this category offers.
Connect an agentWhat we ask in return
A link back, and nothing else. Not a placement fee, not an affiliate arrangement, not a rate card. The widget carries its own credit link; the API and MCP surfaces ask that you attribute the figures where you publish them, so a reader can reach the derivation.
If you are quoting a number in an article, the page it came from carries its formula, its source and the date it was last checked — link to that rather than to the homepage, and your reader can check the figure instead of taking it from you.
Something missing?
If the calculator you need does not exist, ask for it in the chat on the front page. Every question the catalogue cannot answer is recorded, and the ones that come up repeatedly are what gets built next. That queue is the roadmap.