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BMI Calculator

Calculate Body Mass Index from height and weight in metric or imperial units, with the WHO category and the weight range that would land you in the healthy band.

22.9
Healthy weight — within the WHO healthy band
Healthy BMI (18.5–24.9) for this height: 56.7 – 76.3 kg

What BMI Misses

  • Body composition: muscle and bone are denser than fat; BMI treats all weight equally.
  • Fat distribution: central (visceral) fat carries more metabolic risk than hip/leg fat at the same BMI.
  • Ethnic variation: some populations (e.g. South Asian) face elevated risk at lower BMIs; WHO offers adjusted bands of 23/27.5 for those groups.
  • Age: older adults may have better outcomes at slightly higher BMI than the standard band.

The Formula Behind the Result

  1. Choose metric (kg/cm) or imperial (lb/ft+in) units.
  2. Enter your height and weight; BMI is computed as weight divided by squared height.
  3. The result shows your BMI, the WHO weight category, and the weight range that corresponds to the healthy band for your height.
  4. All computation is instant and local — nothing is stored or sent anywhere.
Formula & Technical Standard
BMI = kg/m². Imperial: BMI = 703 × lb/in². WHO bands: <18.5 underweight · 18.5–24.9 healthy · 25–29.9 overweight · ≥30 obese.

Worked Example

Metric example
Input: 70 kg, 175 cm
Output: BMI 22.9 — Healthy weight
22.9 sits mid-band; the healthy range for 175 cm spans roughly 56.7 to 76.3 kg.
Imperial example
Input: 180 lb, 5 ft 10 in (70 in)
Output: BMI 25.8 — Overweight (just above band)
The healthy band for 5'10" tops out near 173 lb, so 180 lb lands 0.8 points into the overweight range.

Common Questions

Is BMI accurate for athletes?

Not very. BMI does not distinguish muscle from fat, so muscular individuals often score "overweight" despite healthy body composition. Athletes should look at body-fat percentage or waist measures instead.

Does BMI apply to children?

No. Children and teens are assessed with age- and sex-specific BMI percentiles, not the adult bands. This calculator implements the adult standard only.

Why is the healthy range so wide?

The 18.5–24.9 band spans a huge weight range (for 175 cm, nearly 20 kg) because it covers many body frames. Treat the band as a coarse population screen, not an individual target.

Where does BMI come from?

Belgian statistician Adolphe Quetelet developed the index in the 1830s (originally the Quetelet index); Ancel Keys popularized the "BMI" name in 1972. It was designed for population statistics, which is why its limits matter.

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