Body mass index bmi calculation - how to calculate body fat percentage

Here's how body mass index (BMI) and body fat percentage are calculated:

How to calculate body mass index (BMI)

Metric unit formula:

BMI = weight (kilograms) ÷ height² (meters)

For example, a person who is 170 centimeters (1.7 meters) tall and weighs 65 kilograms has a BMI = 65 ÷ (1.7 × 1.7) ≈ 22.49.

Imperial unit formula:

BMI = 703 × Weight (lbs) ÷ Height² (inches)

For example, a person who is 5 feet 10 inches (70 inches) tall and weighs 160 pounds has a BMI = 703 × 160 ÷ (70 × 70) ≈ 22.5.

Body fat percentage calculation method

Calculation formula based on BMI:

Men: Body fat percentage = (1.2 × BMI) + (0.23 × age) – 16.2.

Women: Body fat percentage = (1.2 × BMI) + (0.23 × age) – 5.4.

Calculation formula based on waist circumference and weight:

Adult women:

Parameter a = waist circumference (cm) × 0.74

Parameter b = weight (kg) × 0.082 + 34.89

Body fat weight (kg) = a – b

Body fat percentage = (body fat weight ÷ body weight) × 100%.

Adult males:

Parameter a = waist circumference (cm) × 0.74

Parameter b = weight (kg) × 0.082 + 44.74

Body fat weight (kg) = a – b

Body fat percentage = (body fat weight ÷ body weight) × 100%.

These formulas can help you initially estimate your BMI and body fat percentage, but it should be noted that body fat percentage can also be measured by more accurate methods such as skinfold measurement and bioelectrical impedance.