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BMI Calculator — Body Mass Index for Adults, kg/cm or lb/ft

Free BMI calculator for adults in metric or imperial units. See your BMI, its WHO category on a color scale and the healthy weight range for your height.

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BMI is a screening measure for adults aged 18 and over, not a diagnosis. It does not tell muscle from fat or show where fat is stored, so athletes, older adults and pregnant people may get misleading results. Talk to a health professional about your weight and health.

For children and teens, BMI must be compared with age-and-sex growth percentiles; this calculator does not do that and should not be used under 18.

Categories follow the World Health Organization (WHO) adult classification. Some Asian health bodies, following a WHO expert consultation, use lower cut-offs (for example 23 or more as overweight) for people of Asian descent; check the guidance used in your country.

How to use

  1. Choose metric (cm, kg) or imperial (ft, in, lb) units.
  2. Enter your height and weight; the result updates as you type.
  3. Read your BMI, its WHO category on the scale, and the healthy weight range for your height.

Example

Height 175 cm, weight 70 kg → BMI = 70 ÷ 1.75² = 22.9, healthy weight. Healthy range at 175 cm: 56.7–76.3 kg.
Height 5 ft 10 in, weight 160 lb → BMI 23.0, healthy range about 129–173 lb.

Details and limitations

BMI = weight in kg ÷ (height in m)². Imperial values are converted exactly (1 in = 2.54 cm, 1 lb = 0.45359237 kg). The result is rounded to one decimal and that rounded value decides the WHO category: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30–34.9 / 35–39.9 / 40+ obesity class I / II / III.

The calculation runs in your browser; your height and weight are not sent or stored.

FAQ

What is a healthy BMI for adults?

The WHO classes a BMI of 18.5 to 24.9 as a healthy (normal) weight for adults. The calculator shows the weight range that gives this BMI at your height.

Can I use this BMI calculator for my child?

No. For people under 18, BMI has to be compared with growth charts for their age and sex (BMI-for-age percentiles). Ask a pediatrician or use an official child BMI tool.

Is BMI accurate for muscular people?

Not very. BMI uses only height and weight, so muscular people can be classed as overweight without excess fat. Waist measurement and a professional assessment give a fuller picture.

Format references

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