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Calculator

BMI Calculator

Calculate your Body Mass Index from height and weight. Supports metric (cm/kg) and imperial (ft/lb) units. Instant result with WHO category.

This calculator is for informational purposes only and is not medical advice. Consult a healthcare professional for a complete health assessment.

WHO BMI categories

Category BMI range
Underweight < 18.5
Healthy weight 18.5 – 24.9
Overweight 25 – 29.9
Obese (Class 1) 30 – 34.9
Obese (Class 2) 35 – 39.9
Obese (Class 3) ≥ 40

How to use

Select metric or imperial units, enter your height and weight, and the BMI updates automatically. The gauge bar shows where you fall on the scale and the healthy weight range tells you the target zone for your height.

Metric: height in centimetres, weight in kilograms.

Imperial: height in feet and inches, weight in pounds.

Limitations

BMI does not distinguish between fat and muscle mass. Athletes and people with high muscle mass often have elevated BMIs despite low body fat. Conversely, older adults may have normal BMI but high fat percentage due to muscle loss.

These categories apply to adults (18+). For children and teenagers, age- and sex-specific BMI percentile charts are used instead.

Some ethnic groups have higher metabolic risk at lower BMI thresholds — adjusted cut-offs are used clinically in South and East Asian populations.

Frequently asked questions

What is BMI?
BMI (Body Mass Index) is a number calculated from your weight and height. It is used as a screening tool to identify possible weight categories. BMI = weight (kg) / height² (m²). For imperial units, multiply by 703.
What is a healthy BMI range?
According to the WHO, a BMI between 18.5 and 24.9 is considered healthy weight for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
Is BMI accurate?
BMI is a useful population-level screening tool but has well-known limitations for individuals. It does not measure body fat directly and can misclassify muscular athletes (high BMI, low fat) or people with low muscle mass (normal BMI, high fat). Always consult a doctor for a complete assessment.
Is BMI the same for men and women?
The standard BMI formula and categories are the same for adult men and women. However, women naturally carry more body fat than men at the same BMI, so some clinicians use gender-specific body fat reference ranges alongside BMI.
What BMI is considered obese?
A BMI of 30 or above is classified as obese by the WHO. Obesity is further split into Class 1 (30–34.9), Class 2 (35–39.9), and Class 3 or severe obesity (40+).

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