BMI Calculator with Health Categories
Calculate your Body Mass Index from height and weight. See your BMI category (underweight, normal, overweight, obese) and healthy weight range.
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Frequently Asked Questions
How does the BMI Calculator work?
The tool applies the formula BMI = weight(kg) / height(m)^2. If you enter imperial units, it first converts pounds to kilograms (lb / 2.205) and inches to meters (in * 0.0254) before running the formula. The resulting number is compared against WHO threshold ranges to determine your category (underweight < 18.5, normal 18.5-24.9, overweight 25-29.9, obese 30+).
How is BMI calculated?
BMI is your weight in kilograms divided by your height in meters squared (kg/m2). The tool handles the math and unit conversions for you whether you enter metric or imperial measurements.
What are the BMI categories?
Underweight is below 18.5, normal weight is 18.5 to 24.9, overweight is 25.0 to 29.9, and obese is 30.0 and above. These are the standard WHO categories used by most health organizations.
Is BMI accurate for everyone?
BMI is a useful screening tool but does not account for muscle mass, bone density, age, or body composition. Athletes with high muscle mass may have a high BMI despite being healthy. Consult a healthcare provider for a complete assessment.