Body mass index is the most common health number people look up, and also one of the most misunderstood. It is genuinely useful as a quick screen — and genuinely misleading if you treat it as the final word on your health.
TL;DR — Enter your height and weight in the BMI calculator to see your BMI, your category and a healthy weight range. It is informational, not a diagnosis.
What BMI actually measures
BMI is simply your weight divided by your height squared. It estimates whether your weight is in a healthy range for your height, and sorts the result into bands: underweight, normal, overweight and obese. Because it needs only two easy numbers, it is a cheap way to flag people who might benefit from a closer look.
What the categories mean
The standard adult bands are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 or above obese. At a population level, being well outside the normal band is linked to higher health risks. But these are statistical guides drawn from large groups — they describe averages, not individuals.
Where BMI falls short
BMI’s big blind spot is that it cannot tell muscle from fat. A lean, muscular athlete and someone carrying excess fat can share the same BMI. It also does not account for where you carry weight, and it behaves differently across ages, sexes and ethnicities — the same number can mean different things for different people.
Use it as a starting point
The honest way to use BMI is as one signal among several. Pair it with your body fat percentage and your waist-to-hip ratio for a fuller picture, and treat any concern as a reason to talk to a clinician — not a self-diagnosis. Run your number in the BMI calculator to see your category and healthy range.