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⚖️ BMI Calculator

Calculate your Body Mass Index instantly — with metric & imperial support, visual gauge, ideal weight range, health tips, and calculation history.

Enter Your Measurements
Age (years, optional)
yrs
Sex (optional)
Height
cm
Range: 50 – 280 cm
Weight
kg
Range: 1 – 500 kg
BMI Categories (WHO)
Underweight < 18.5
Normal weight 18.5 – 24.9
Overweight 25.0 – 29.9
Obese Class I 30.0 – 34.9
Obese Class II 35.0 – 39.9
Obese Class III ≥ 40.0
Source: World Health Organization (WHO)
History
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Quick BMI Check
Enter BMI to see category:
Formula
Metric:
BMI = kg / m²
Imperial:
BMI = (lbs / in²) × 703

About BMI

What is BMI?

Body Mass Index (BMI) is a simple numerical measure calculated from a person's height and weight. It was developed by Adolphe Quetelet in the 19th century and adopted by the WHO as a population-level screening tool — not a direct diagnostic of body fat or health.

Limitations

BMI does not distinguish fat from muscle mass, so athletes may score as "overweight." It also does not account for fat distribution (visceral vs. subcutaneous), age-related changes in body composition, or ethnic differences in risk thresholds. Always consult a healthcare professional for a full assessment.

Children & Teens

For ages 2–19, BMI is interpreted using age- and sex-specific percentile charts (BMI-for-age) rather than the fixed adult cut-offs. This tool uses adult WHO categories; for children, always use a paediatric growth chart or consult your doctor.

Asian Cut-offs

The WHO has proposed lower BMI thresholds for Asian populations — overweight at ≥ 23 and obese at ≥ 27.5 — due to higher metabolic risk at lower BMI values compared to Western populations. Some national guidelines in Asia use these adjusted cut-offs.