Privacy policy

Last updated Oct 16, 2026.

What we collect

• No accounts and no sign-up forms on the site.
• Cloudflare Web Analytics. Our host, Cloudflare, adds a small analytics script to pages. It measures page views and performance (page address, referrer, browser type, load timing and country derived from IP) without cookies and without building advertising profiles. See Cloudflare Web Analytics and Cloudflare's privacy policy.
• Server logs. Cloudflare processes standard request data (such as IP address) to deliver and protect the site.

What stays in your browser

• Calculator entries are processed in your browser. They aren't put in page addresses and aren't sent to us or to the analytics script.
• If you click Save assumptions, they're stored in your own browser's local storage. Clear your site data to remove them.
• The 3D labs run entirely in your browser.

Email

Correction reports and school requests are sent from your own email app only when you press send. We use them to fix content and verify listings, and we don't sell or publish contact details.

Changes

If we add accounts, advertising or an email list, we'll update this page first.