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BMI Calculator
Free adult BMI calculator in kg/cm or lb/ft. See your BMI on a colour scale and the healthy weight range for your height, with the WHO scale or the lower cut-offs for South and East Asian adults.
Your BMI
For adults 18 and over. Not for pregnancy, children or very muscular athletes.
Your BMI
How BMI works
- BMI = weight in kg ÷ (height in metres)². For example 70 kg and 1.75 m: 70 ÷ 3.06 = 22.9.
- WHO adult ranges: under 18.5 below the healthy range, 18.5 to 24.9 healthy, 25 to 29.9 overweight, 30 and over obesity.
- For people of South Asian, Chinese and other Asian backgrounds, WHO and NICE use lower lines: 23 and 27.5, because health risks start at a lower BMI.
✅ Rules last checked:
📚 Official sources: WHO: Obesity and overweight fact sheet · NICE PH46: BMI for Black, Asian and minority ethnic groups
We build every tool from the official rules and re-check them when they change. Always confirm with the official source before you rely on a result.
🛠️ Spotted a mistake or an out-of-date rule? Tell us
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Questions people ask
What is a healthy BMI?+
For most adults, 18.5 to 24.9. For South Asian, Chinese and other East Asian adults, NICE and the WHO suggest health risks start from 23.
Is BMI accurate?+
It's a useful quick check for most adults, but it can't tell muscle from fat and doesn't look at where fat is stored. Waist size and other checks with a doctor give a fuller picture.
Can I use it for children or in pregnancy?+
No. Children and teens need age- and sex-specific charts, and BMI isn't used to judge weight in pregnancy. Ask a doctor or midwife.