BMI Calculator

How to use the BMI calculator

1. Choose metric (kg / cm) or imperial (lb / in).
2. Enter your weight and height, then press Calculate if JavaScript is disabled — the result updates automatically otherwise.
3. Read your BMI value, its WHO category and the healthy weight range for your height.

The benefit is speed and privacy: you get a screening number instantly, nothing is stored, and the result is shareable as a link. Use it to start a conversation about trends and body composition, not as a diagnosis.

What BMI measures

Body Mass Index is weight in kilograms divided by height in metres squared (kg/m²). The World Health Organization bands used above are: under 18.5 (underweight), 18.5–24.9 (normal range), 25–29.9 (overweight) and 30 or above (obesity). It is a quick screening tool for populations, not a diagnosis for an individual.

How to read your result

A single BMI reading is less useful than a trend over time. The healthy weight range shown for your height is the weight that would place you inside the 18.5–24.9 band. Waist circumference, body composition, blood pressure and other markers can add context that BMI cannot. If your result surprises you, measure again under the same conditions and look at the direction over weeks rather than one day.

Limitations

BMI does not distinguish muscle from fat, so athletes and very muscular people can be classified as overweight. It is not validated for pregnancy, children, frail older adults or some ethnic groups with different risk thresholds. It also says nothing about where fat is stored or about metabolic health. If you are pregnant or planning pregnancy, BMI is not the right screening tool; ask your clinician. Use it as one input, not a verdict, and discuss any concerns with a qualified professional. This calculator is informational only and is not medical advice.

Frequently asked questions