BMI calculator
Work out your body mass index in seconds, and get an honest explanation of what it actually means.
What the categories mean
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
These are the ranges used by the NHS and the World Health Organization for adults.
What BMI doesn't tell you
BMI is height and weight, nothing more. It cannot distinguish muscle from fat, so a rugby player and someone carrying excess weight can share a BMI while being in completely different health. It says nothing about where fat sits on your body, and visceral fat around the organs carries more risk than fat elsewhere.
It is also less reliable for some groups. People of South Asian, Chinese and some other Asian backgrounds face increased health risks at lower BMI values, and UK guidance suggests using a lower threshold for those groups. It is not designed for children, pregnant women or people over 65 without adjustment.
Treat BMI as one rough signal among several. Waist measurement, how you feel, energy levels and blood markers all tell you more.
If you want to change your number
Weight change comes down to sustained energy balance over months, not weeks. Our calorie calculator works out how much you need day to day and emails you a seven-day plan to start from. If you'd rather track as you go, meal tracking in the app does the arithmetic for you.