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The Body Mass Index (BMI) is one way to measure body size. It's a tool to estimate body fat and screen for whether people have overweight or obesity, and health risks associated with their weight.1
You can use the BMI calculator above to divide your weight in kg by your height in metres and compare your result to the BMI classes. Enter your height, weight and age and check your results in the table below.1 Click on a BMI class to learn more.
It's important to know that this classification can vary in certain ethnic groups, such as Indigenous Peoples, South Asians, Chinese and other populations. Always check with your healthcare professional about the suitability of this BMI classification based on your own circumstances.1
| Classification | BMI |
| Underweight | Below 18.5 |
| Normal | 18.5–24.9 |
| Overweight | 25.0–29.9 |
| Obesity | 30 and above |
| Class I | 30.0–34.9 |
| Class II | 35.0–39.9 |
| Class III | 40 and above |
This BMI calculator is for adults 20 years or older. Talk to your doctor about your BMI if you're under the age of 20.1
BMI is a good way to check your risk of diseases related to body fat. Living with overweight or obesity is associated with an increased risk of mortality and other diseases or conditions.2 Generally, the higher your BMI, the greater the risk of developing other chronic weight-related diseases, including:2-19
Ask a doctor for more information about any of these diseases and how they relate to your BMI.
BMI is a simple and objective measurement, but it can be misleading in certain cases and for some groups of people. Research has shown that BMI is less accurate in predicting the risk of disease in people who are older, athletes, those who are tall or short, and those with more muscular body types. For example, elite athletes or bodybuilders have more muscle and weigh more, which makes their BMI higher.20,21
BMI also doesn't take into account:12,20
It's important to remember that living with overweight or obesity doesn't necessarily mean you're unhealthy, just as being at a ‘normal’ weight doesn't mean you're healthy. Your BMI doesn't define you, but knowing and understanding your BMI can be a powerful tool for taking charge of your own health.
Regardless of your BMI, healthcare professionals recommend having a healthy diet and lifestyle. Talk to a doctor about your weight and health and evaluate what actions may be needed.
People living with overweight or obesity have a higher risk of developing cardiovascular disease (CVD), also known as heart disease.22
Although both BMI and Waist-to-Height Ratio (WtHR) can be used to assess a person’s risk of developing CVD, WtHR is considered to be a stronger predictor of cardiovascular risk factors, such as high blood pressure and high cholesterol.23,24
BMI is used to indicate a person’s weight category, based on their height and weight. WtHR, on the other hand, is used to measure the distribution of a person’s body fat, based on their height and waist circumference. Measuring WtHR is important, as an excess level of fat stored around the belly, in particular, is associated with an increased risk of developing heart disease.23,24
Knowing both your BMI and WtHR can help you to improve your heart health by understanding whether action should be taken to manage your weight.
Click here to calculate your Waist-to-Height Ratio and learn what this means for you.
Obesity isn't a matter of willpower. It's a complex condition influenced by genetics, hormones and other biological factors.
Essential tools to monitor your health and have productive conversations with a doctor.
Talk to a doctor about treatment options that could help prevent the weight you lose from coming back.
