What is BMI?

Body Mass Index (BMI) is a simple measurement using your weight and height to work out if your weight is healthy. The BMI calculation divides an adult's weight in kilograms by their height in metres squared.

BMI Formula

BMI = weight (kg) ÷ height² (m²)

BMI Categories

  • Underweight: BMI less than 18.5
  • Normal weight: BMI 18.5 to 24.9
  • Overweight: BMI 25 to 29.9
  • Obese: BMI 30 or greater

Important Considerations

  • BMI is a useful measurement for most people over 18.
  • It is not applicable to children, pregnant women, or highly muscular athletes.
  • Your ethnicity can affect your risk of some health conditions, so BMI thresholds may be different.
  • BMI should be considered alongside other factors like diet, exercise levels, and family history.