BMI (Body Mass Index) is a widely used health indicator measuring the relationship between weight and height, recommended by the World Health Organization.

Gender

Age

yrs

Height

Weight

🧮 Deurenberg Body Fat Formula

Body Fat % = (1.20 × BMI) + (0.23 × Age) − (10.8 × Sex factor) − 5.4

BMICalculated from height and weight

AgeIn years; valid range 15–80

Sex factorMale = 1, Female = 0 (corrects physiology)

ResultPercentage (%) of body weight that is fat

Note: Published by Dutch nutritionist Deurenberg et al. in 1991, this formula applies to typical adults (not professional athletes). Body fat is influenced by muscle mass, hydration and bone density — the formula gives a statistical estimate with ±3–5% error and should not replace professional body composition measurement (DEXA, bioelectrical impedance).

📖 BMI Classification (WHO)

Underweight< 18.5

Normal18.5 – 24.9

Overweight25.0 – 29.9

Obese≥ 30.0

❓ FAQ

What is BMI?

BMI = weight (kg) ÷ height² (m²). It is the standard indicator for assessing whether an adult's weight is in a healthy range.

How is body fat percentage calculated?

This tool uses the Deurenberg formula: BF% = (1.20 × BMI) + (0.23 × Age) − (10.8 × Sex) − 5.4, where male = 1 and female = 0. The result is an estimate for reference only.

Are there limitations to BMI?

Yes. BMI cannot distinguish between fat and muscle, so it may be inaccurate for athletes, elderly people or pregnant women. Combining it with body fat percentage gives a better picture.

Are the thresholds different for Asians?

Some Asian countries recommend lower cutoffs — overweight at ≥23.0 and obese at ≥27.5. This tool follows the standard WHO thresholds.