BMI calculator
Calculate BMI from height and weight and see which range the result falls into.
How to calculate BMI
1. Enter height in centimeters.
2. Enter weight in kilograms.
3. Read your BMI and category.
4. Treat the result as a starting point for talking to a professional, not as a diagnosis.
Examples
Weight in the normal range
At 170 cm and 65 kg, BMI is about 22.5 — in the “normal weight” category on the simplified WHO scale for adults.
Overweight range
At 170 cm and 80 kg, BMI is about 27.7 — in the overweight category. The number alone does not describe body fat or fitness.
Tracking over time
You can return every few weeks and compare results — remembering that weight naturally fluctuates.
When BMI can help
• As a quick, rough indicator for adults.
• When you want to compare your result with general WHO ranges.
• As a starting point before seeing a doctor or dietitian.
Where BMI came from
Body mass index is a population tool — it was built to compare groups, not to fully diagnose an individual. WHO popularized reference ranges for adults. Modern medicine also looks at waist size, body composition, activity, and other health factors alongside BMI.
Frequently asked questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². Example: 70 ÷ (1.75 × 1.75) ≈ 22.9.
What are the WHO categories?
Underweight < 18.5; normal 18.5–24.9; overweight 25–29.9; obesity ≥ 30 (simplified for adults).
Is BMI reliable for everyone?
It is a simplified index — it does not account for muscle, age, sex, or health status.
Is the result a diagnosis?
No. It is educational information, not a medical finding.
What units should I use?
Height in cm, weight in kg.