Privacy

ConstantID sets no cookies and loads no third-party scripts, fonts, images or trackers; portraits and diagrams are served from this site. Links to NIST, Wikimedia Commons and other sources take you to those sites, which have their own policies.

Stored in your browser: only your display choices (how many significant figures to show, and the last unit conversion you set up), saved in this browser's local storage so they are still there next time. They never leave your device, are not cookies, and you can clear them in your browser settings at any time.

Your browser may store two small preferences on your own device (the significant figures you last chose in the calculation panel, and the last unit converter settings). They never leave your device and you can clear them with your browser's site data.

If this ever changes, for example if advertising or affiliate links are added, this page will say so before it happens.

Server logs

Like almost every website, the server keeps a log of requests: the time, the page requested, the referring page, the browser's user-agent string, and a shortened network address (the last part of the IP address is removed before anything is written, so the log cannot point to one connection). The log is used only to count visits and to stop abuse, is never shared or sold, and is deleted after 30 days. The legal basis under the GDPR is legitimate interest in running and securing the site.

The hosting proxy in front of this site (measured 2026-10-26): successful requests are not logged there. Requests that fail at the proxy are recorded with the visitor's IP address and browser user-agent, with cookies and authorization headers redacted, and are currently kept until the proxy is restarted. A retention limit for those records is under review.