How BMI is calculated
Body mass index compares your weight with your height:
BMI = weight (kg) ÷ height (m)²
In imperial units, it’s weight (lb) × 703 ÷ height (in)². This calculator handles both, so just pick your units.
WHO adult BMI categories
- Under 18.5: underweight
- 18.5–24.9: healthy weight
- 25–29.9: overweight
- 30 and above: obese range
The marker on the colour scale shows where you sit. The healthy weight range shows the weights that give a BMI of 18.5–24.9 at your height.
What BMI is good for
BMI is quick, free and useful for spotting trends across large groups. For an individual, it’s a reasonable first screening tool. It’s linked with risks such as high blood pressure and type 2 diabetes at the population level.
What BMI misses
- Muscle vs fat. A strong lifter and an inactive person can have the same BMI with very different health.
- Where fat is stored. Fat around the waist carries more health risk than fat elsewhere. A waist measurement adds useful information.
- Ethnicity. Many South Asian adults face higher metabolic risk at lower BMIs, so some guidelines use lower cut-offs.
- Age and sex. Body composition naturally changes with age.
For a fuller picture, estimate your body fat with the body fat calculator and check your ideal weight range.
Next steps
If your BMI is above the healthy range, a modest loss of 5–10% of body weight can meaningfully improve blood pressure, blood sugar and cholesterol. Set a realistic goal date with the transformation timeline, or let a coach guide you through our weight loss program.
BMI is a screening tool, not a diagnosis. Speak with your doctor about your individual health.
