Last updated 13 September 2026
This site does not know who you are, and it is built so that it cannot find out. Nothing you measure ever leaves your device.
Nothing. The ruler is drawn in your browser and the thing you hold against the screen is never photographed, recorded, or transmitted. There is no server to send it to: the site is a set of files, and every page is finished before it reaches you.
If you set the scale with a bank card, the resulting figure is saved in your own browser so the ruler is right when you come back. Your theme choice is saved the same way. Both stay on your device, are readable only by this site, and are removed if you clear your browser data. No copy is sent anywhere.
We count visits, so we know whether anyone is using this. That is done with PostHog, on its European servers, configured to record as little as it can: page views only, with your address truncated before it is stored, no session recording, and no capture of what you click or type.
When something breaks we collect the error with Sentry, on its European servers, so it can be fixed. Reports are stripped of request contents, cookies, headers and any user identifier before they are sent.
Ads pay for this site. They are served by Google, which may set cookies and use them to choose what to show you. Google’s use of that information is governed by its own policies, which you can read at policies.google.com/technologies/partner-sites. If you are in the United Kingdom or the European Economic Area you will be asked for consent before any non-essential cookie is set, and you can change that choice at any time.
The site is served by Cloudflare, which processes your address in order to deliver the page and to block attacks. That processing is necessary for the site to work at all.
Delivering the site rests on our legitimate interest in it working and staying available. Counting visits and collecting errors rest on our legitimate interest in knowing whether the site is used and whether it is broken, which is why both are configured to collect as little as possible. Advertising cookies rest on your consent, which is why you are asked.
Visit counts and error reports are kept for as long as the free tiers of those services retain them, which is a matter of months rather than years. What is stored in your own browser stays until you clear it.
Under UK and EU data protection law, and under India’s Digital Personal Data Protection Act, you may ask what is held about you, ask for it to be corrected or deleted, object to it being processed, and complain to your data protection authority.
In practice there is very little to ask for. We hold no name, no email address, no account, and no untruncated address, so in most cases we would be unable to find anything that belongs to you even if you asked. That is the intended outcome rather than an evasion. The one thing entirely in your control is the data in your own browser, which you can delete by clearing this site’s data.
This is a ruler. It is not aimed at children, and it collects nothing that would identify anyone of any age.
For anything in this policy, including a request about your data, use the feedback form. It reaches the person who runs this site.
If this policy changes, the date at the top changes with it. There is no mailing list to notify, because we do not have your address.