BMI Calculator
Check your Body Mass Index in metric or imperial units and see where it falls on the WHO scale — with honest notes on what BMI can't tell you.
What BMI measures
Body Mass Index is a quick screening number that relates weight to height. It was designed for tracking populations, and it remains useful for individuals as a first orientation: values far outside the healthy range correlate with higher health risks.
BMI = weight (kg) ÷ height² (m²) · Imperial: BMI = 703 × lb ÷ in²
WHO categories for adults
- Below 18.5 — underweight
- 18.5–24.9 — healthy weight
- 25.0–29.9 — overweight
- 30.0 and above — obesity
Limitations to keep in mind
BMI cannot see body composition. Muscular people often have a "high" BMI with low body fat, while a normal BMI can hide low muscle mass. It is also not designed for children and teens (they use age-adjusted percentiles) or during pregnancy.
Disclaimer
This calculator is for general information only and is not medical advice. For an assessment of your individual health, consult a qualified healthcare professional.
Frequently asked questions
How is BMI calculated?
BMI = weight in kilograms divided by height in meters squared. In imperial units the formula is 703 × weight in pounds ÷ height in inches squared.
What is a healthy BMI range?
For most adults the World Health Organization defines 18.5–24.9 as the healthy range, 25–29.9 as overweight, and 30 and above as obesity.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes can score "overweight" while being lean, and it applies differently to children, pregnant women and the elderly. It is a screening indicator, not a diagnosis.
Should I make health decisions based on BMI alone?
No — BMI is one signal among many. Waist circumference, body composition, blood markers and overall lifestyle matter more. Discuss results with a healthcare professional.