About Health calculators
Quick health maths without an account or an upload: your Body Mass Index from height and weight in metric or imperial units, and bedtimes or wake-up times spaced across full 90-minute sleep cycles. Everything is calculated on your own device, so personal numbers never leave it.
These are planning estimators, not medical advice. BMI is a screening number, not a diagnosis, and sleep needs differ from person to person. Check the assumptions on each page and talk to a professional about anything that worries you.
Frequently asked questions
Are these calculators medical advice?
No. They run the standard published formulas on the numbers you enter. They estimate, they do not diagnose, and they are no substitute for a doctor.
Is my weight or health data uploaded?
No. Every health calculator here runs inside your browser, so the numbers stay on your device and disappear when you close the page.