BMI Calculator

Body Mass Index is the world’s most common health-screening number: one division that turns height and weight into a single figure anyone can interpret. This calculator computes your BMI, places you in a WHO weight category, shows the healthy weight range for your height, and marks your position on a colour gauge.

The math is simple — BMI equals weight in kilograms divided by the square of height in metres — but the interpretation needs care. For adults, the WHO cut-offs are: under 18.5 underweight, 18.5 to 24.9 healthy, 25 to 29.9 overweight, and 30 and above obese. These bands were designed for population-level screening, not individual diagnosis. Muscle weighs more than fat, so a muscular build can land “overweight” while being perfectly fit; conversely, a normal BMI can still hide excess body fat. Children, older adults and athletes need different yardsticks altogether.

The healthy-weight readout is often more useful than the single BMI number. It tells you the weight span that keeps your BMI between 18.5 and 24.9 at your height — for a 175 cm adult, roughly 56.7 to 76.3 kg. Weight naturally fluctuates a couple of kilos day to day; the question that matters is whether the trend sits inside that span, not whether any one reading is “ideal”.

One more caveat the single number hides: where fat sits matters as much as how much of it there is. Belly (visceral) fat carries more metabolic risk than fat stored on the hips and thighs, which is why two people at BMI 27 can have very different health profiles. That is also why some guidelines use lower action points — overweight from 23, obese from 27.5 — for Asian populations, who tend to carry more body fat at a given BMI.

For non-scale ways to track health, many clinicians now pair BMI with waist circumference or waist-to-height ratio, plus sleep, activity and blood-pressure trends. And for calorie planning alongside this, the Calorie Calculator estimates what your body burns each day — the other half of the energy-balance equation.