How Does It Work?
- Pick your unitsMetric uses centimetres and kilograms; imperial uses feet, inches and pounds. Switching converts nothing you typed — just enter the numbers you know.
- Enter height and weightThe result updates as you type. Height in feet and inches is entered in two boxes so you do not have to convert first.
- Read the number and the rangeYou get the BMI value, the category it falls in, and the weight range that would put you in the healthy band at your height.
What Is It Used For?
Body mass index compares weight against height on a single scale, which makes it a quick population-level screening number. It is not a measure of health on its own: it says nothing about body composition, so a muscular athlete and a sedentary person of the same weight get the same figure. Treat it as one indicator among several rather than a verdict.
- A quick check of where your weight sits relative to your height.
- Filling in a health questionnaire or insurance form that asks for BMI.
- Setting a target weight range before starting a fitness plan.
- Converting between metric and imperial when a chart uses the other system.
- Tracking a trend over months, which is more meaningful than any single reading.
Examples
| Height | Weight | BMI | Category |
|---|---|---|---|
| 175 cm | 70 kg | 22.9 | Healthy weight |
| 175 cm | 55 kg | 18.0 | Underweight |
| 175 cm | 85 kg | 27.8 | Overweight |
| 5 ft 9 in | 154 lb | 22.7 | Healthy weight |
| 160 cm | 80 kg | 31.3 | Obese (class I) |