BMI Calculator

Calculate your body mass index (BMI) in metric or imperial units. The calculator shows your BMI, your WHO category, where you sit on the BMI scale, and the healthy weight range for your exact height.

How to calculate BMI

1. Pick metric (cm/kg) or imperial (ft/in/lb).
2. Enter your height and weight. Use the sliders for quick adjustment or type exact values.
3. Read your BMI and category. The visual scale shows exactly where you fall between the four WHO ranges.

BMI categories (WHO adult)

• Under 18.5 — Underweight
• 18.5 to 24.9 — Healthy weight
• 25 to 29.9 — Overweight
• 30 and above — Obese

BMI formula

BMI = weight (kg) ÷ height (m)². In imperial units, BMI = (weight in lb × 703) ÷ (height in inches)². The calculator handles either system and converts internally.

When BMI is misleading

BMI doesn't distinguish muscle from fat. Athletes and people with high muscle mass can register as 'overweight' even when their body fat is low. BMI is also less reliable for adults over 60, pregnant people, and very tall or very short people. Pair BMI with body-composition measures (waist circumference, waist-to-height ratio) for a fuller picture.