BMI calculator
Your Body Mass Index and category in metric or imperial — plus the caveat most BMI tools leave out: it can't tell muscle from fat.
BMI categories
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
Read it honestly: BMI uses only height and weight, so it can't see body composition. If you lift, you may read "overweight" while carrying little fat. Treat BMI as one rough signal, not a verdict.
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Frequently Asked Questions
How is BMI calculated?
BMI = weight in kilograms divided by height in metres squared (kg/m²). Categories: under 18.5 = underweight, 18.5–24.9 = normal, 25–29.9 = overweight, 30+ = obese. This calculator converts imperial units for you.
Is BMI accurate?
As a quick population screen, it is useful. For an individual it has a real blind spot: it only uses height and weight, so it cannot distinguish muscle from fat. A lean, muscular person can land in the "overweight" range while carrying very little fat, and someone "normal" by BMI can still have high body fat.
Should athletes use BMI?
Take it with a grain of salt. If you lift or carry above-average muscle, BMI will overstate your risk. Waist circumference, body-fat percentage, and how your clothes fit are better individual signals.
What is a healthy BMI?
The "normal" range is 18.5–24.9. But within that range, body composition (how much is muscle vs fat) matters more for health and how you look than the exact number.
General educational information, not medical advice. BMI is a screening tool, not a diagnosis.