Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a widely used screening tool that uses your height and weight to estimate body fat. It serves as a simple, inexpensive way to categorise individuals into weight groups that may be associated with certain health risks.
BMI Categories Explained
- Underweight (Below 18.5): May indicate nutritional deficiencies or underlying health concerns.
- Healthy Weight (18.5 – 24.9): Generally associated with lower risk of chronic diseases.
- Overweight (25.0 – 29.9): May increase the risk of conditions like hypertension or type 2 diabetes.
- Obese (30.0 and above): Suggests a higher volume of body fat, which is linked to increased long-term health risks.
Important Limitations
While BMI is a helpful guideline, it is not a diagnostic tool. It does not account for body composition. For example, athletes with high muscle mass may have a high BMI despite having very low body fat. Always consult a healthcare professional for a complete health assessment rather than relying solely on a BMI number.
Frequently Asked Questions
Not entirely. BMI doesn't distinguish between muscle and fat, so it can overestimate body fat in muscular people and underestimate it in older adults who've lost muscle mass. It's a useful starting point, not a diagnosis.
Metric: weight in kilograms divided by height in metres squared. Imperial: weight in pounds divided by height in inches squared, multiplied by 703.
Enter your height above and the calculator will show the weight range that keeps your BMI between 18.5 and 24.9, the range generally considered healthy for most adults.
No. Children and teenagers need age- and sex-specific BMI percentile charts, not the adult categories used here. Speak to a GP or paediatrician for a child's healthy weight range.