BMI Calculator

What is BMI?

Body Mass Index (BMI) is a widely used numerical value calculated from a person's weight and height. It provides a simple, reliable indicator of body fatness for most people and is used by health professionals worldwide as a screening tool for weight categories that may lead to health problems.

BMI Categories (WHO Standard)

• Underweight: BMI below 18.5 — May indicate malnutrition, eating disorders, or other health issues.
• Normal weight: BMI 18.5–24.9 — Generally associated with the lowest health risks.
• Overweight: BMI 25.0–29.9 — Associated with increased risk of cardiovascular disease and type 2 diabetes.
• Obese Class I: BMI 30.0–34.9 — Moderate obesity; significantly increased health risks.
• Obese Class II: BMI 35.0–39.9 — Severe obesity; high health risk.
• Obese Class III: BMI 40.0+ — Very severe obesity; very high health risk.

How BMI is Calculated

Metric formula: BMI = weight (kg) ÷ height² (m²)

Imperial formula: BMI = 703 × weight (lbs) ÷ height² (inches²)

Limitations of BMI

While BMI is a useful screening tool, it has some well-known limitations:

• Muscle mass: Athletes and highly muscular individuals may have a high BMI without excess body fat.
• Age: Older adults tend to have more body fat than younger adults at the same BMI.
• Sex: Women generally have more body fat than men at the same BMI.
• Ethnicity: Health risks associated with BMI can vary across different ethnic groups.

Privacy & Security

All BMI calculations are performed entirely in your browser. No personal data (weight, height, or age) is ever sent to our servers or stored anywhere. Your health information remains completely private.