【BMI Calculator】Is your weight within the normal range?

BMI Calculator

 Enter your height and weight, find out if your weight is within the normal range.
BMI calculator

What is BMI?

BMI (Body Mass Index) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults.

Several researches show raised BMI is a major factor for increased future risk to obesity-related diseases, such as hypertension , diabetes , cardiovascular disease , stroke , fatty liver , sleep apnea , etc.

Classification of Weight by BMI

Proposed classification of weight by BMI in adult Asians [Reference: Regional Office for the Western Pacific (WPRO), World Health Organization 2000]

BMI [Unit: kg/m²]Classification of Weight
< 18.5Underweight
18.5 - 22.9Normal
23 - 24.9Overweight
25 - 29.9Obesity (Moderate)
≥ 30Obesity (Severe)

The above reference has been recommended by the WHO Western Pacific Region for Asian adults and is not applicable to children under age 18 or women who are pregnant.

How to maintain a Healthy BMI?

Overweight and obesity is now a global concern. Department of Health (Hong Kong) interview more than 4,000 Chinese adults in 2016, it is reported that 18.1% are overweight (BMI between 23-24.9) and 21% are obese (BMI above 25).

To control body weight, it is essential to develop healthy eating habits and make exercise a habit.

  1. Healthy Diet - Reducing Calories absorption

    • Monitor and control the daily intake of fats, sugars and sodium - 1 High 3 Low Diet

    • Cut down on processed food (e.g. spam and ham)

    • Cut down on high in oil and deep-fried foods

    • Cut down on foods high in fat, salt, sugar and cholesterol

    • Eat more vegetables, fruits, whole wheat and grains, beans and nuts

  2. Regular Exercise - Burning Calories

    Exercise blasts excess fats - reducing the mortality and morbidity risk. WHO recommends adults should do at least 150 mintues of moderate-intensity aerobic physical activities throughout the week, such as jogging, brisk walking and cycling.

    How to monitor the workout intensity? It can be gauged with a simple talk test. If you are able to carry on a conversation comfortably while engaging in the activity, the intensity is moderate. If you become winded or out of breath when carrying on a conversation, it is vigorous.

    According to WHO recommendation, weight loss in a safe and healthy speed should be about 1-2 pounds per week. You need to burn 3,500 calories extra to lose 1 pound. However, you should be alert if you are losing weight too quickly, whether it is a water weight loss or fat loss. Extreme weight loss may imposes a burden to your heart.

It is suggested to consult your dietitian and doctor for a suitable weight management program and treatment if you still cannot achieve the ideal BMI by the diet plans and physical training.

BMI Calculation

BMI = Weight (kg) ÷ Height (metres) ÷ Height (metres)

For example, a 1.6 metre-tall lady weighs 55 kg, her BMI is

BMI = 55 (kg) ÷ 1.6 (metres) ÷ 1.6 (metres) = 21.48 (kg/m²)

Although BMI is widely used to classify overweight and obesity, it does not always reflect the fat to muscle ratio. For the following 2 types of adults, it may not accurately measure overweight and obesity.

  1. Athletes / Body Builders(More muscle mass)
  2. Elderly(Less muscle mass)

Moreover, the above BMI calculation does not apply to children and adolescence under 18. Because there are changes in weight and height with age, BMI levels among children and adolescence need to be expressed relative to other children of the same sex and age. For more details, please consult your Paediatrician or Dietitian .

The BMI calculator is for reference only and is not intended as a substitute for medical professional help or advice.


  1. World Health Organization. The Asia-Pacific perspective: redefining obesity and its treatment. Health Communications Australia Pty Limited; 2000.
  2. World Health Organization. Global recommendations on physical activity for health. WHO Press; 2010.
  3. WebMD. Body Mass Index (BMI) for Adults.
  4. World Health Organization. BMI classification.
  5. Department of Health (Hong Kong). Classification of Physical Activity and Level of Intensity.
  6. Hospital Authority (Hong Kong). 理想BMI防病工程.
  7. Centre for Health Protection, Department of Health (Hong Kong). Body Mass Index (BMI) Distribution.
  8. World Health Organization. Obesity and overweight.
  9. Diabetes Hong Kong. 運動治療.