Understanding BMI: A Complete Guide
The short answer
Body mass index (BMI) is weight in kilograms divided by height in metres squared. It is one screening measure, not a diagnosis or a direct measurement of body fat.
- Severe Thinness: < 16
- Moderate Thinness: 16 – < 17
- Mild Thinness: 17 – < 18.5
- Normal: 18.5 – < 25
- Overweight: 25 – < 30
- Obese Class I: 30 – < 35
- Obese Class II: 35 – < 40
- Obese Class III: ≥ 40
Adults 20+ · WHO
A reproducible calculation
Body mass index (BMI) is weight in kilograms divided by height in metres squared. It is one screening measure, not a diagnosis or a direct measurement of body fat.
Imperial inputs are converted using 1 lb = 0.45359237 kg and 1 in = 2.54 cm. Five feet nine inches is 69 inches, not 5.9 feet.
- Weight
- 150 lb = 68.0388555 kg
- Height
- 5 ft 9 in = 175.26 cm
- Your BMI
- 22.1509004 → 22.2 kg/m²
Units are converted before calculation. Categories use the unrounded result; only the display is rounded. The shortcut multiplier 703 can differ slightly from exact conversion.
Adult (20+), not pregnant. For ages 2–19, use a validated BMI-for-age calculator. This tool shows adult ranges only. BMI is one screening measure, not a diagnosis or a weight goal. It does not distinguish muscle from fat and is not suitable for pregnancy.
The standard adult BMI formula is the same for women and men. The same BMI does not establish the same body composition or personal health risk.
This explanation checks the method and arithmetic. It does not claim an independent medical review. Personal interpretation requires context and an appropriate healthcare professional.
Sources below are in English.
Body mass index (BMI) is weight in kilograms divided by height in metres squared. It is one screening measure, not a diagnosis or a direct measurement of body fat.
Adults 20+. For ages 2–19, use a validated BMI-for-age calculator. This tool shows adult ranges only.
BMI is one screening measure, not a diagnosis or a weight goal. It does not distinguish muscle from fat and is not suitable for pregnancy.
The standard adult BMI formula is the same for women and men. The same BMI does not establish the same body composition or personal health risk.
A reproducible calculation
Imperial inputs are converted using 1 lb = 0.45359237 kg and 1 in = 2.54 cm. Five feet nine inches is 69 inches, not 5.9 feet.
150 lb = 68.0388555 kg
5 ft 9 in = 69 in = 175.26 cm = 1.7526 m
BMI = 68.0388555 / 1.7526² = 22.1509004 kg/m² → 22.2 kg/m²
Units are converted before calculation. Categories use the unrounded result; only the display is rounded. The shortcut multiplier 703 can differ slightly from exact conversion.
This explanation checks the method and arithmetic. It does not claim an independent medical review. Personal interpretation requires context and an appropriate healthcare professional.
Sources
Sources below are in English.