What is BMI?
Body Mass Index (BMI) is a number calculated from your weight and height. It is widely used as a quick screening tool for weight categories that may be linked to health risk, but it does not measure body fat directly and does not account for muscle, bone, or individual circumstances.
How to Calculate BMI
- Weigh yourself in kilograms (kg).
- Measure your height in meters (m), or centimeters (cm) ÷ 100.
- Divide weight by height squared: BMI = kg ÷ m².
- Compare the result to standard categories below.
BMI Categories
- Underweight: BMI below 18.5
- Normal: BMI 18.5 up to 25
- Overweight: BMI 25 up to 30
- Obese: BMI 30 or higher
Ranges follow common WHO-style cutoffs for adults. Children, athletes, and pregnancy need different assessments.
Example
Weight 70 kg, height 175 cm (1.75 m): BMI = 70 ÷ 1.75² ≈ 22.9, in the Normal range.
FAQ
- What is a healthy BMI?
- For many adults, BMI between 18.5 and 25 is often described as the normal range. Your ideal range can differ based on age, sex, ethnicity, and health—use this tool for orientation only.
- How accurate is BMI?
- BMI is useful for population trends but imperfect for individuals. It can misclassify very muscular people or miss risk when weight is normal but body composition is unfavorable.
- Is this tool free?
- Yes. SmartFlexa’s BMI calculator is free with no signup.
- Is my data secure?
- Your weight and height stay in your browser; we do not send them to our servers for this calculation.
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