BMI calculator
Body mass index, its WHO category and the weight range considered healthy for your height.
Result
- BMI
- 22.9
- Category (WHO, adults)
- Normal weight
- Healthy weight for your height
- 56.7 kg – 76.3 kg
- BMI prime
- 0.91
How this was calculated
Body mass index
BMI = weight (kg) ÷ height (m)²
70 ÷ 1.75² = 22.86
Healthy range
18.5 × height² to 24.9 × height²
56.7 kg to 76.3 kg
What this calculation assumes
- For adults aged 20 and over. Children and teenagers are assessed with age- and sex-specific percentiles instead.
- Categories follow the World Health Organization: under 18.5 is underweight (thinness), 18.5–24.9 normal, 25–29.9 overweight, and 30 or more obese (classes I, II and III from 30, 35 and 40).
- BMI does not tell muscle from fat and can mislead for athletes, older people and some ethnic groups. It is a screening number, not a diagnosis: talk to a health professional about your own health.
The formula
BMI = weight (kg) ÷ height (m)²
In US units the same formula becomes BMI = 703 × weight (lb) ÷ height (in)². A person 175 cm tall weighing 70 kg has a BMI of 70 ÷ 1.75² = 22.9.
The World Health Organization classes adult BMI as underweight below 18.5, normal from 18.5 to 24.9, overweight from 25 to 29.9 and obese from 30. The healthy range shown for your height is 18.5 × height² to 24.9 × height².
What BMI does not tell you
BMI uses only height and weight. It cannot tell muscle from fat or where fat is carried, so it can overstate risk for muscular people and understate it for others. Some health bodies use lower cut-offs for people of Asian descent. It is a screening figure for adults, not a diagnosis.
Questions people ask
Is BMI accurate for children?
No. For ages 2 to 19 BMI is compared with growth charts for the same age and sex, which this calculator does not do.
What is BMI prime?
Your BMI divided by 25, the upper limit of the normal range. Under 1.0 is within or below normal.