Health & Fitness4 min read•Updated 2026-09-04
BMI Formula & Healthy Weight Categories for Adults and Teens
Calculate Body Mass Index (BMI) using metric or imperial units and understand WHO weight category classifications.
MX
MultiToolX Technical Team
Health Analytics Team
Key Takeaways
- Metric Formula: BMI = weight (kg) / [height (m)]².
- Imperial Formula: BMI = [weight (lbs) x 703] / [height (inches)]².
- WHO Categories: Underweight (<18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obesity (≥30).
1. How Body Mass Index is Calculated
BMI is a screening metric used by healthcare providers to assess weight relative to height:
- Metric: Divide weight in kilograms by height in meters squared.
- Imperial: Multiply weight in pounds by 703, then divide by height in inches squared.
Frequently Asked Questions
Does BMI distinguish between muscle mass and body fat?
BMI is a screening tool and does not directly measure body fat percentage. Athletes with high muscle mass may have a higher BMI while maintaining low body fat.
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