Privacy Policy
1. Controller
Matthias Henkert, Birkenstraße 52c, 16321 Bernau b. Berlin, Germany. Email: mail@stackbrain.de
2. No data collection in the calculator
This BMI calculator processes all input exclusively in your local browser. No personal data — height, weight, age, sex, country, waist or hip circumference, body-fat percentage — is transmitted to our servers or to any third party. No cookies are set; no third-party tracking is used.
Your colour-theme preference (light/dark) is stored locally in your browser via localStorage; it is not transmitted to us.
3. Hosting
This website is hosted at Hostinger. The host records standard request log files (IP address, timestamp, user agent, referrer, HTTP status, transferred volume). Logs are overwritten after at most 7 days. Legal basis: Article 6(1)(f) GDPR — legitimate interest in operating a secure website.
4. Web analytics (Umami)
This website uses Umami, a privacy-friendly, open-source analytics tool that we self-host on a server in Germany. Umami sets no cookies, uses no fingerprinting, and collects no personal data. It records aggregated, anonymous information only: page URL, referrer, browser, operating system, device type, and country (derived from a truncated IP, then discarded). The data is not shared with any third party and is never combined with your input into the calculator.
We use this data to understand which calculators and articles are useful so we can improve them. Legal basis: Article 6(1)(f) GDPR — our legitimate interest in measuring the reach of our content. You can object at any time per Article 21 GDPR, e.g. by enabling a browser ad-blocker, which will block the Umami script.
5. Fonts
Fonts (DM Sans, DM Mono) are bundled with the site and served from the same domain. No connection to third-party font servers (such as Google Fonts) is established. Your IP address is never transmitted to a font provider.
6. Your rights
Under the GDPR you have the right of access, rectification, erasure, restriction of processing, data portability, and the right to lodge a complaint with a supervisory authority. Contact: mail@stackbrain.de