How to Calculate Your BMI: A Step-by-Step Guide

Body Mass Index (BMI) is a simple calculation using your weight and height to estimate body fat. The formula is: BMI = weight (kg) / height² (m²).

Step 1: Convert Weight to Kilograms

If your weight is in pounds (lbs), multiply by 0.4536 to get kilograms.

Example: 150 lbs × 0.4536 = 68.04 kg.

Step 2: Convert Height to Meters

If your height is in feet and inches:

1. Convert feet to inches: multiply feet by 12.
2. Add the remaining inches.
3. Multiply total inches by 0.0254 to get meters.

Example: 5 ft 9 in → (5 × 12) + 9 = 69 inches → 69 × 0.0254 = 1.7526 m.

Step 3: Calculate BMI

Divide your weight in kilograms by the square of your height in meters.

Example: 68.04 kg / (1.7526 m)² = 68.04 / 3.0716 ≈ 22.1.

Step 4: Interpret Your BMI (WHO Classification)

• Underweight: BMI < 18.5
• Normal weight: BMI 18.5 – 24.9
• Overweight: BMI 25 – 29.9
• Obesity: BMI ≥ 30

Note: BMI is a screening tool, not a diagnostic measure. It does not distinguish between muscle and fat. Consult a healthcare professional for a complete assessment.