When you use a calculator

The sizing engine is code that runs in your browser. When you press “Calculate”, the arithmetic happens on your device and the result is shown on your device. No measurement is sent over the internet at any point.

You can check this yourself: open your browser’s developer tools, choose the Network tab, and calculate a size. No request carries your measurements.

Saving results to this device

If you choose “Save to this device”, the result is stored in your browser’s local storage under the key ukbsc.tracker.v1. Each saved result contains the date, your four measurements (in inches), what you were wearing, your sizes, the confidence level and the methodology version.

This data never leaves your browser and we cannot see it. Delete it from the size tracker, one result or all at once, or by clearing this site’s data in your browser settings.

Share links

A share link looks like this:

https://www.example.co.uk/#m=32F&t=36C&c=high&v=1.0.0&s=round

It contains your modern and traditional sizes (m, t), the confidence level (c), the methodology version (v) and, if you chose one, your breast shape (s). It never contains measurements.

Everything is after the # symbol. Browsers don’t send that part of a link to the website’s server, and our analytics record the page path only. Nothing about the link is stored by us. Anyone you give the link to can see the sizes in it.

Printing and downloading

The printable size card and the downloadable image are created in your browser. They show sizes only, not measurements, and nothing is uploaded.

AI-assisted tools

The fit diagnosis tool, the style suggestions in your results and the question box in step-by-step measuring send a small request to our server, which passes it to our AI provider, Anthropic, to generate a reply.

What is sent

• Fit diagnosis: the problems you tick, the size you wear, your measured size and breast shape if you add them, and your note.
• Style suggestions: your calculated size, breast shape and the need you choose.
• Measuring questions: your question, the step you’re on and the unit selected.

Before any typed text is sent, numbers are removed and replaced with “[number removed]”, except bra sizes such as 34DD. This happens in your browser and again on our server.

What is never sent

• Your measurements.
• Your IP address, or any identifier, to the AI provider.
• Anything from other pages or tools.

What we keep

We don’t store requests or replies, and we don’t log their content. To stop the AI tools being overused, our server keeps a one-way hash of your IP address in memory for up to an hour, counting requests (up to 20 an hour). It is not written to disk and is discarded when the server restarts.

Analytics

We use Plausible Analytics, a cookie-free analytics service that does not collect personal data or track you across websites. It records which pages are visited and a small set of events such as “Calculation Completed”. Events record that something happened, never what was calculated or entered. We send the page path only, without anything after ? or #.

Hosting

Like any website, our hosting provider receives standard technical information when your browser requests a page, such as IP address, browser type and the page requested, and may keep it briefly in server logs for security and reliability. Your measurements are never part of these requests.

Cookies

This site does not set cookies. Saved results use local storage, which you control, as described above.

If you email us

If you contact us, we receive your email address and whatever you write, and use it only to reply. Please don’t send measurements, photos or health details: we don’t need them to help.

Children

This site does not create accounts or collect personal information from anyone. Our first bra guide is written for parents and carers and contains no measuring tools.

Your rights

Under UK data protection law you can ask what personal data we hold about you and ask us to delete it. Because measurements and saved results never reach us, in practice the only personal data we might hold is an email you have sent us. Contact us about any privacy question.

Changes to this page

If how the site handles data changes, we’ll update this page and the date at the top before the change goes live.