BMI Calculator
Know your Body Mass Index in seconds

Your BMI Result
Healthy BMI range: 18.5 - 22.9 kg/m²
The Sterling Hospitals BMI Calculator is a quick, reliable tool designed to help you understand your body mass index and take a proactive step toward your wellness goals. Whether you are tracking your general health, planning a fitness routine, or seeking personalised medical guidance, calculating your BMI is a helpful starting point. Enter your height and weight below to instantly calculate your score, view your health category, and discover dedicated care pathways guided by our expert clinical teams.
What is BMI?
Body Mass Index (BMI) is a screening measure used to assess a person’s weight in relation to their height. It is calculated using a person’s weight and height and is commonly used to classify weight into categories such as underweight, healthy weight, overweight, and obesity in adults.
BMI can provide a general indication of whether a person’s weight falls within a particular range. However, it does not directly measure body fat or provide a complete picture of an individual’s health. Factors such as muscle mass, age, sex, and fat distribution can affect how BMI should be interpreted.
For this reason, BMI is best considered as one part of an overall health assessment rather than a standalone measure of health.
How Is BMI Calculated?
Body Mass Index (BMI) is calculated using a person's weight and height. The standard formula for adults is:
BMI = Weight (kg) ÷ Height² (m²)
For example, if you weigh 70 kg and are 1.75 metres tall:
BMI = 70 ÷ (1.75 × 1.75) = 22.9
You can use the BMI calculator above to calculate your BMI without performing the calculation manually. Your result can then be compared with standard adult BMI categories.
Understanding Your BMI Result
Your BMI result indicates which standard weight category your height and weight fall into. It can be a useful starting point for understanding your weight in relation to your height, but it should not be interpreted as a diagnosis or a complete measure of your health.
Underweight (Below 18.5)
A BMI below 18.5 is generally classified as underweight. A lower BMI may be associated with inadequate nutrition or certain underlying health conditions in some people. However, BMI alone cannot determine whether a person is underweight for medical reasons.
If you have an unexpectedly low BMI or have experienced unintentional weight loss, speaking with a doctor may help identify whether further assessment is appropriate.
Healthy Weight (18.5–24.9)
A BMI between 18.5 and 24.9 is generally considered to be within the healthy weight range for adults.
However, being within this range does not necessarily mean that a person has no health risks. BMI does not measure body fat directly or account for factors such as muscle mass, fat distribution, or overall fitness.
Overweight (25.0–29.9)
A BMI between 25.0 and 29.9 is generally classified as overweight.
A higher BMI may be associated with an increased risk of certain health conditions, particularly when other risk factors are present. Your doctor can help interpret your BMI alongside factors such as waist circumference, blood pressure, blood sugar, cholesterol levels, medical history, and lifestyle.
Obesity (30.0 or Higher)
A BMI of 30 or higher is generally classified as obesity in adults. Based on BMI, obesity is further classified into three classes:
- Class 1 Obesity: BMI 30.0–34.9
- Class 2 Obesity: BMI 35.0–39.9
- Class 3 Obesity: BMI 40.0 or higher
Higher levels of excess body weight may be associated with an increased risk of several health conditions. However, BMI alone does not establish an individual's overall health or determine the cause of excess weight.
If your BMI falls within this range, a healthcare professional can help assess your overall health and discuss appropriate weight-management approaches based on your individual needs.
Weight Management and Treatment Options
Weight management is not limited to achieving a particular BMI. The appropriate approach depends on factors such as your BMI, overall health, medical history, lifestyle, and any health conditions associated with your weight. A healthcare professional can assess these factors and recommend an approach suited to your individual needs.
Weight management may include:
- Nutrition and dietary counselling: A nutritionist or dietitian can help develop an appropriate eating plan based on your nutritional needs, health conditions, and weight-management goals.
- Lifestyle changes: Regular physical activity, healthy eating habits, adequate sleep, and other sustainable lifestyle changes can support healthy weight management.
- Medical weight management: Depending on your health and individual circumstances, a doctor may recommend medical interventions, including weight-management medicines where appropriate.
- Management of associated health conditions: If excess or inadequate weight is associated with other health concerns, your healthcare team may also address conditions such as diabetes, high blood pressure, or abnormal cholesterol levels as part of your overall care.
- Bariatric surgery: For some people with obesity who meet specific clinical criteria, bariatric surgery may be considered when other weight-management approaches have not provided sufficient results. A specialist assessment is required to determine whether surgery is appropriate.
The goal of weight management is to support overall health and well-being through an approach that is safe, sustainable, and appropriate for the individual.
At Sterling Hospitals, our team of nutritionists, physicians, and bariatric specialists is available to guide this process from initial assessment through ongoing care. Book an appointment with a Sterling Hospitals specialist to discuss BMI results and weight-management options.
Limitations of BMI
BMI can be a useful screening measure, but it does not provide a complete picture of a person’s health or body composition. Several factors can affect how accurately a BMI result reflects an individual’s health status:
- Does not measure body fat directly: BMI is based on height and weight and does not distinguish between fat, muscle, bone, or other body tissues.
- May not reflect muscle mass: Individuals with a higher muscle mass, such as athletes, may have a higher BMI despite having relatively low body fat.
- Does not show where body fat is stored: BMI does not account for fat distribution, including abdominal fat, which may be relevant when assessing certain health risks.
- Interpretation can vary by age and sex: Body composition changes with age, and BMI may not fully reflect these differences. Standard adult BMI categories also do not account for all differences in body composition between males and females.
- Does not assess overall health: BMI does not consider factors such as blood pressure, blood glucose, cholesterol levels, medical history, physical activity, or dietary habits. A healthcare professional may consider these factors along with BMI for a more comprehensive health assessment.
Disclaimer: This BMI calculator is intended for general screening purposes only and should not be considered a substitute for professional medical advice, diagnosis, or treatment. For a comprehensive assessment of your health and weight, consult a qualified healthcare professional.
Frequently Asked Questions
Is BMI an accurate measurement for everyone?
BMI is a helpful screening tool for the general population, but it does not account for muscle mass, bone density, age, or metabolic health. It should be evaluated alongside other clinical measurements by a healthcare professional.
How often should I check my BMI?
Checking your BMI during your annual wellness exam is generally sufficient unless you are actively following a weight management plan recommended by your physician.
What should I do if my BMI is outside the healthy range?
If your result falls in the underweight, overweight, or obesity categories, consider discussing your overall health, diet, and lifestyle with your primary care provider.
Is BMI different for men and women?
The standard BMI formula and adult BMI categories are generally the same for men and women. However, BMI does not account for differences in body composition, such as muscle mass and fat distribution. Your BMI may therefore need to be considered alongside other health factors for a more complete assessment.
Is BMI different for children and adults?
Yes. Although the BMI formula is the same, BMI is interpreted differently for children and adolescents. Since body composition changes as children grow, their BMI is assessed in relation to their age and sex using growth charts or BMI-for-age percentiles rather than the standard adult BMI categories.
Can BMI be used during pregnancy?
BMI is not generally used to assess weight status during pregnancy in the same way as it is for non-pregnant adults. Healthcare professionals may consider a woman's pre-pregnancy or early-pregnancy BMI, along with other factors, when monitoring weight and overall health during pregnancy.
What is the difference between BMI and body fat percentage?
BMI is calculated using a person's height and weight and is used to classify weight into standard categories. Body fat percentage refers to the proportion of a person's body weight that is made up of fat. Unlike BMI, body fat percentage provides an estimate of body composition, although the accuracy can vary depending on the method used to measure it.
What is a healthy BMI for older adults?
The standard adult BMI categories can be used as a general reference for older adults, but BMI may not provide a complete picture of health or body composition as people age. Changes in muscle mass and body fat distribution can affect BMI interpretation. A healthcare professional can consider BMI along with other health and nutritional factors when assessing an older adult.
Does BMI determine whether I need to lose or gain weight?
No. BMI alone does not determine whether you need to lose or gain weight. Your appropriate weight-management goals depend on factors such as your overall health, medical history, body composition, lifestyle, and any associated health conditions. A healthcare professional can help determine whether weight change is appropriate and recommend a suitable approach.
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