Privacy notice

What stays on your device

Every calculator and simulator on this site runs entirely in your browser as JavaScript. Formulas, measurements, chemical structures and data you paste in are processed there rather than on a server. There is no account system, no login, and no database of user input.

Because results are encoded into the page address so they can be shared, the values you enter appear in the URL. That address, values included, can reach this site’s server, for example when you reload the page or follow a link to another page here, and on pages with advertising it is part of the request Google receives for an ad. Cloudflare’s analytics, described below, leaves the values out. Treat a link with your values in it the way you would treat a shared spreadsheet, and do not enter anything confidential.

What is stored in your browser

Your browser’s storage is used to remember the following. None of it is transmitted, and clearing your browser data removes it entirely.

• Theme choice: whether you selected light or dark.
• Consent choice: your answer to the cookie prompt, and when it was given, so you are not asked repeatedly.
• Recent and pinned tools: the tools you opened most recently and any you pinned, so they can be offered to you again.
• Unit preferences: the unit you last chose for each kind of quantity, so the calculators open in it next time.
• Interface state: such as whether you dismissed a banner during this session, or turned down the offer to add the site to your home screen.
• 3D anatomy models: each model you have opened, kept in the browser’s cache so it does not have to download again. They can be large, so the viewer shows how much space a stored model takes and has a button to remove it.

Server logs

The web server records standard request logs, which include IP address, the page requested, timestamp, referrer and browser user-agent. These are used for security and to diagnose faults. They are not linked to any identity and are not used to build a profile. The page requested and the referrer are full addresses, so they can include the values from a tool, as described above.

Analytics

Page views, including those on embedded tools, are counted with Cloudflare Web Analytics. For each view, Cloudflare records the page, the site that linked to it, the reader’s country, browser, operating system and type of device, and how quickly the page loaded. Cloudflare says it uses no cookies or local storage to collect these, and does not fingerprint individual readers. Cloudflare also says it does not record the query string, which is the part of the address where a tool keeps the values you enter.

Advertising

This site shows advertising from Google so that the tools can stay free. Google and its partners may set cookies and use device identifiers to select and measure ads. Outside the European Economic Area, the United Kingdom and Switzerland, ads may be personalised unless you decline.

If you are in the European Economic Area, the United Kingdom or Switzerland, personalised advertising is switched off by default and only enabled if you agree. Declining does not restrict any tool; you simply see non-personalised advertising instead. You can change your answer at any time using the privacy choices link, which is also in the footer of every page.

Google’s own description of how it uses information from sites that use its services is published at policies.google.com/technologies/partner-sites.

Embedded tools

Tools on this site can be embedded into other pages as an iframe. Those embedded views carry no advertising. Page views, including embedded ones, are counted with Cloudflare Web Analytics, which Cloudflare says uses no cookies and does not fingerprint individual readers. If you are using a tool embedded in someone else’s page, that page has its own privacy practices which are outside our control.

Children

These tools are used in schools. No account is required and no personal information is requested, so beyond the server logs described above, no personal data about a child is collected by this site. Where advertising is shown, it is a general audience placement rather than one directed at children.

Your rights

Because no account or personal profile is created, there is typically no personal data held about you to access, correct or delete beyond the server logs described above. If you believe there is, or you want to exercise a right under the GDPR, UK GDPR or a comparable law, get in touch and it will be handled within the statutory period.

Accuracy of results

Results are provided for education and general use. Constants and atomic weights are taken from published sources and the source is stated on the relevant tool, but calculations should be independently verified before being relied upon for anything safety-critical, clinical or regulatory.

Changes

If this notice changes in a way that affects how your data is used, the consent prompt is shown again rather than relying on a previous answer.