BMI calculator (body mass index)

What BMI is

Body mass index relates your weight to your height: it's your weight in kilograms divided by your height in meters squared. Adolphe Quetelet proposed it in the 19th century, and today the World Health Organization uses it to classify adult weight in population studies.

What BMI doesn't measure

BMI doesn't know what your weight is made of. A kilo of muscle and a kilo of fat count the same, so someone who lifts can come out as overweight while being lean, and someone with little muscle can come out as normal weight with high body fat. It also doesn't say where fat is stored, and abdominal fat is the kind most linked to cardiovascular risk.

• It doesn't tell muscle from fat.
• It ignores where fat is distributed.
• It isn't equally valid for children, pregnant women, older adults or athletes.
• The categories were designed for populations, not to judge an individual.

That's why, if you train, your body fat percentage or your waist-to-height ratio will tell you much more (ideally, your waist should be less than half your height).

BMI is a general reference for adults, not a diagnosis. To assess your health, talk to a healthcare professional.

Look beyond your weight

From a single photo, Gymia's analysis estimates your body fat and rates your muscularity, definition and proportions: exactly what BMI can't see.