BMI
Enter height and weight, and the body mass index is worked out.
Units
BMI
23.3
Normal weight
- Weight for an index of 18.5 to 2556.8 to 76.8 kg
- Ponderal index13.3
Weight divided by height cubed. Not skewed by height the way BMI is.
The scale
- Below 18.5 – underweight
- 18.5 to 25 – normal weight
- 25 to 30 – overweight
- 30 to 35 – obesity, class I
- 35 to 40 – obesity, class II
- Above 40 – obesity, class III
A calculator, not an assessment of health. The measure does not tell muscle from fat and does not apply to children, pregnancy or athletes.
How it works
BMI is weight in kilograms divided by height in metres squared. The measure was devised in the 1830s by Adolphe Quetelet to describe how weight is spread across a population, not to judge individuals. It survives because it needs only two measurements that are easy to take.
The World Health Organization boundaries for adults are 18.5 and 25, with 30 for obesity. They are set at population level and do not apply to children, pregnancy, or anyone with an unusual amount of muscle. Several Asian countries use lower boundaries, because risk rises earlier there.
The measure does not tell muscle from fat and says nothing about where on the body the weight sits. A well-trained person can land high with nothing wrong, and someone with little muscle can land in the middle with a good deal of abdominal fat. Waist measurement says more about that.
BMI also gives systematically high values for tall people and low ones for short people, because the body grows in three directions while the denominator counts only two. The ponderal index, which divides by height cubed, corrects for that and is shown here alongside.
The weight range under the answer is the set of weights that give an index between 18.5 and 25 for your height. It is a consequence of the formula, not a recommendation.
This is a calculator, not an assessment of your health. What a value means for you is a question for a clinician.