Privacy
No accounts, no sign-up, no database of visitors.
Calculators and charts
The blood type calculator, Punnett square, charts and simulators run entirely in your browser. The blood types you pick are not sent anywhere.
Saved in your browser
The calculator remembers your last parent selections in your browser’s localStorage (key bt:calc) so they’re there when you come back. It never leaves your device.
AI questions
If you use an “Ask” box, your question (and, on the calculator, the current result) is sent to our server and passed through Vercel AI Gateway to an AI model to write the answer. We don’t store questions or answers. Your IP address is held briefly in memory only to limit abuse. Don’t include names or other personal details.
Analytics
We use Ahrefs Web Analytics, a cookieless, privacy-friendly analytics tool, to count page views. It does not use cookies or track you across sites.
Medical disclaimer
This site is for education. It is not medical advice and doesn’t replace your doctor, midwife or blood bank.