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BMI Calculator

Calculators · Added 4 July 2026

Body Mass Index compares weight to height with a single number. Enter your measurements in either metric or imperial units to see your BMI, the World Health Organization category it falls into, and the weight range that would put you in the healthy band at your height.

Units
cm
kg

How to use the bmi calculator

  1. 1Choose metric (cm / kg) or imperial (ft, in / lb).
  2. 2Enter your height and weight.
  3. 3Read your BMI value and the category it falls into.
  4. 4The healthy weight range for your height is shown underneath for context.

Examples

Metric

Input
Height 175 cm · Weight 72 kg
Result
BMI 23.5 — Normal weight (healthy range 56.7–76.3 kg)

Imperial

Input
Height 5 ft 9 in · Weight 185 lb
Result
BMI 27.3 — Overweight

About the bmi calculator

What BMI is good for, and what it isn't

BMI was devised in the 1830s by Adolphe Quetelet as a way of describing populations, not individuals. It became a clinical shorthand because it needs only two measurements that anyone can take, and it correlates reasonably well with body fat across large groups.

That population-level usefulness does not transfer cleanly to a single person. BMI ignores muscle mass, bone density, fat distribution, age and sex. Two people with identical BMIs can have very different health risks, and the number says nothing at all about fitness, diet quality or blood markers.

Better measurements to pair it with

Waist circumference is a stronger predictor of metabolic risk than BMI, because abdominal fat is the kind most closely linked to cardiovascular and diabetes outcomes. Waist-to-height ratio — keeping your waist under half your height — is a simple and surprisingly robust check.

If your BMI falls outside the normal band, treat it as a prompt for a conversation rather than a verdict. A clinician can add blood pressure, lipid profile, blood glucose and body composition to build a picture that a single ratio never could.

Frequently asked questions

What are the BMI categories?
The WHO classification for adults is: under 18.5 underweight, 18.5 to 24.9 normal weight, 25.0 to 29.9 overweight, and 30.0 or above obese. Some health authorities in Asia apply lower thresholds, treating 23 as the start of the overweight range, because cardiometabolic risk rises at a lower BMI in South and East Asian populations.
Is BMI accurate for athletes?
No. BMI cannot distinguish muscle from fat, so a well-trained athlete frequently scores in the overweight or obese band while carrying very little body fat. It is a population-level screening measure, not a diagnosis.
Does BMI work for children?
Not with these thresholds. Children and teenagers are assessed against age- and sex-specific percentile charts, because healthy body composition changes rapidly through growth. This calculator is intended for adults aged 20 and over.
What is the formula?
Metric: weight in kilograms divided by height in metres squared. Imperial: weight in pounds divided by height in inches squared, multiplied by 703. Both produce the same number for the same person.

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