BMI calculator
Mass over height squared, and what the categories mean.
- Body mass index22.86
- WHO categoryNormal range
- Normal-range weight at this height56.7–76.6 kg
- BMI prime0.914
BMI prime is your BMI divided by 25 — above 1 is above the WHO normal range. It exists because a single ratio travels better between populations than a category name does.
What BMI is, and what it isn’t
BMI is one division: your mass in kilograms by the square of your height in metres. Adolphe Quetelet published it in 1832 as a way of describing populations, and it was never designed to say anything about an individual. It is on this page because it is asked for constantly and because the arithmetic is easy to get subtly wrong — not because it is a measure of health.
It cannot tell muscle from fat, so it reads a sprinter and a sedentary person of the same mass identically. It ignores where that mass sits, which is the part that actually tracks with risk. And because the square is an empirical fit rather than a geometric fact, it runs slightly high for tall people and low for short ones. A category from this page is a position in a lookup table, not a diagnosis.
Where it does not apply at all
The WHO bands used here are for adults. Children and teenagers are read against age-and-sex percentile charts instead, and a fixed cut-off will simply be wrong for them. The bands are also known to sit differently across populations — several health bodies use lower thresholds for people of South Asian descent, for instance. Pregnancy, high muscle mass and older age each move the meaning again.
This page does arithmetic. If you want to know what your number means for you, that is a conversation with a doctor, who can weigh it against everything this page has no way of knowing.
Boundaries are half-open
A BMI of exactly 25.0 is “overweight” here, not the top of the normal range, and exactly 30.0 is “obese class I”. That is the WHO’s own convention and it is the single most common reason two calculators disagree about the same person.
