What this site measures.
Last updated 6 October 2026.
Your calculator inputs
Calculations run in your browser. Our analytics events do not include your entered numbers, pasted datasets, custom event names, calculation results, or search terms.
Website analytics
We use a self-hosted Umami instance to measure page visits, referring sites, approximate location, browser, and device information. We also record actions such as using a calculator, changing an interactive table, opening a reference, printing, and following links within the site.
These custom events include the page, tool or resource identifier, action type, and site release. Search events record a result count and a coarse query-length category. Search query parameters are excluded from the tracker’s page URLs.
Optional feature interest
If you choose an option in a paid-feature interest check, we record the option and displayed price. There is no purchase, account, email signup, or payment collection attached to this check.
Practice progress
Guided practice stores your question choices and first-attempt results in this browser using local storage. It does not require an account and is not synchronized between devices. Use the start-again button to clear the saved attempt, or clear site data in your browser. If browser storage is unavailable, you can still practice without saving progress.
Learning analytics record controlled question identifiers, first-attempt correctness, completion counts, solution openings and optional helpfulness choices. They do not include free-text answers or entered data. Resuming and restarting practice are recorded as actions; a completed practice sequence is not a grade or proof of learning.
External services
The analytics script is delivered through a Cloudflare-hosted proxy to our Umami instance. Mathematical typesetting styles and fonts are served with the site. Hosting and these service providers process requests to deliver the site and its assets.
Controlling analytics
You can block analytics requests in your browser. The calculations and resources continue to work when analytics is unavailable. We do not require analytics to use a tool.