How BMI Is Calculated
BMI = weight (kg) ÷ height (m)² or BMI = 703 × weight (lbs) ÷ height (in)²
Example: 70 kg at 175 cm → 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy range.
WHO BMI categories (adults)
- Below 18.5 — Underweight
- 18.5 – 24.9 — Healthy weight
- 25 – 29.9 — Overweight
- 30 and above — Obese
BMI Limitations You Should Know
BMI is a quick screening tool — not a diagnosis. It cannot distinguish muscle from fat, so muscular athletes may register as "overweight" while carrying very little body fat. It also applies differently to children and teens (age/sex percentiles are used), pregnant women, and adults over 65. Combine BMI with waist circumference, body-fat measurement and professional advice for the full picture.
Planning your nutrition next? Try our Calorie Calculator to find your daily energy needs.
Frequently Asked Questions
How is BMI calculated?
BMI = weight in kilograms ÷ height in meters squared. Example: 70 kg at 1.75 m → 22.9. In imperial: BMI = 703 × pounds ÷ inches².
What is a healthy BMI?
18.5 to 24.9 per the WHO. Below 18.5 is underweight, 25–29.9 overweight, 30+ obese.
Is BMI accurate for everyone?
It's a screening tool, not a diagnosis — it can't distinguish muscle from fat and applies differently to children, pregnant women and the elderly. Consult a professional for a full assessment.
What is my healthy weight range?
The weight span keeping your BMI between 18.5 and 24.9 for your height — shown automatically above. Example at 1.75 m: about 56.7–76.3 kg.