Why use Keep Your Body
- Built on official formulas. WHO BMI categories, the Mifflin–St Jeor equation, Naegele's rule, the US Navy body fat method and EFSA water guidance.
- Clear and honest. Each tool explains how the number is worked out, what it means and what it cannot tell you, with sources.
- Private. Health information is personal. Everything is calculated on your device; nothing is sent to us.
- For everyone. Metric and imperial units, Asian BMI cut-offs, Hijri dates and five languages including Arabic.
Important
These calculators provide general information and estimates. They do not diagnose or treat any condition and are not a substitute for advice from a doctor, midwife or dietitian. If you are worried about your health, please speak to a professional.
Frequently asked questions
Are the calculators free?
Yes, with no sign-up. The site is supported by advertising.
Who writes the content?
Our guides summarise guidance from public health bodies such as the WHO, NHS, CDC and EFSA, and list their sources at the end of each page.
Do you store my health data?
No. See our privacy policy.
Can I suggest a calculator?
Yes, through our contact page.