Calculate your Body Mass Index (BMI) using your height and weight. This helps estimate whether you are underweight, normal weight, or overweight.
✔ BMI classification • ✔ Healthy weight range • ✔ Metric & Imperial • ✔ Instant results
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25 – 29.9 | Overweight |
| 30+ | Obese |
BMI (Body Mass Index) is a simple measurement that compares your weight to your height. It is widely used by healthcare professionals, researchers, and public health organisations as a quick way to assess whether a person's weight falls within a healthy range.
BMI does not directly measure body fat, but it can provide a useful indication of whether someone may be underweight, a healthy weight, overweight, or obese.
BMI is calculated using your weight in kilograms and your height in metres.
Formula:
BMI = Weight (kg) ÷ Height² (m²)
For example:
This BMI result would fall within the healthy weight range.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity Class I |
| 35.0 – 39.9 | Obesity Class II |
| 40.0+ | Obesity Class III |
Maintaining a healthy BMI may reduce the risk of several health conditions, including:
A healthy BMI is only one part of overall health. Exercise, nutrition, sleep, stress management, and lifestyle choices are also important.
Although BMI is widely used, it is not a perfect measurement.
BMI does not distinguish between muscle, fat, bone, and water weight.
For example:
Because of these limitations, BMI should be viewed as a general screening tool rather than a complete assessment of health.
BMI calculations for children and teenagers are interpreted differently from adults because age and sex affect body development.
Special growth charts are normally used by healthcare professionals when assessing BMI in children and adolescents.
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered healthy.
Is BMI accurate?
BMI provides a useful estimate but does not directly measure body fat or overall fitness.
Can athletes have a high BMI?
Yes. Athletes often have greater muscle mass, which can increase BMI despite low body fat levels.
Does age affect BMI?
BMI is interpreted differently for children and teenagers. For adults, the standard BMI categories are generally used.
Should I worry about a high BMI?
A high BMI may indicate increased health risks, but it should be considered alongside other health measurements and lifestyle factors.
Health-related information is based on publicly available guidance and commonly accepted medical and health calculation methods.
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Last Updated: August 2026