How we calculate BMI

Passo dopo passo

1. 1

   Convert weight to kilograms (1 lb = 0.4536 kg).

2. 2

   Convert height to meters (1 in = 0.0254 m; 1 ft = 0.3048 m).

3. 3

   Square the height in meters (multiply it by itself).

4. 4

   Divide the weight in kilograms by the squared height.

5. 5

   The result is your BMI in kg/m². Compare to WHO categories.

Fonti autorevoli

Every claim on this page is backed by an authoritative source.

• WHO — Obesity and overweight →
• CDC — Adult BMI Calculator →
• NIH — Calculate Your Body Mass Index →

Ipotesi

What we take to be true when applying this formula.

• Adults 20 years or older. For children and teens, BMI is age- and sex-specific (percentile).

• Standard WHO BMI categories apply. Asian populations may need different cutoffs (per WHO 2004).

• Height and weight are accurate measurements (self-reported values reduce accuracy).

Limiti

What this method does NOT capture.

• BMI does not distinguish between muscle mass and fat mass. Athletes often have high BMI but low body fat.

• BMI does not account for fat distribution. Visceral (belly) fat is more dangerous than subcutaneous fat.

• BMI may misclassify older adults (who tend to lose muscle) and pregnant women.

• Ethnic differences in body composition mean standard cutoffs may not apply equally to all groups.

Ultima revisione: 2026-06-15 • Reviewed by: CalcxApp editorial team