BMI Calculator

How BMI Is Calculated

BMI is calculated with a simple formula:

• Metric: BMI = weight (kg) ÷ (height (m))²
• Imperial: BMI = 703 × weight (lb) ÷ (height (in))²

For example, a person weighing 70 kg and 175 cm tall has a BMI of about 22.9, which falls in the normal weight category.

BMI Categories (World Health Organization)

• Underweight: below 18.5
• Normal weight: 18.5 – 24.9
• Overweight: 25.0 – 29.9
• Obese: 30.0 and above

Limitations of BMI

BMI is a screening tool, not a diagnostic one. It does not measure body fat directly and can be misleading for:

• Athletes and highly muscular people (BMI may be high despite low body fat)
• Older adults (muscle loss can hide fat gain)
• Children and teenagers (different growth charts are used)
• Pregnant women (not applicable)
• Different ethnic groups (risk thresholds may vary)