BMI Calculator — Body Mass Index, Category & Healthy Weight

Height

Height in centimetres

Weight

Weight in kilograms

Enter your height and weight to see your BMI.

About the BMI Calculator

Body Mass Index (BMI) is a simple, widely used measure that relates your weight to your height. It gives a single number that places you in one of four broad categories — underweight, normal, overweight or obese — which health services around the world use as a quick screening check for weight-related health risk. This calculator also works out the healthy weight range for your height: the span of weights that would keep your BMI between 18.5 and 24.9.

Switch freely between metric and imperial — the result is the same, just converted.

BMI is a screening tool: it can't tell muscle from fat, so athletes may read high.

It isn't suitable for children, pregnant women or the very elderly — see a professional.

How it works

Three steps. No sign-up, no upload, no wait.

Enter your height

Pick metric (cm) or imperial (ft + in) and type your height.

Enter your weight

Switch between kilograms and pounds, then type your weight.

Read your BMI

See your BMI, category and the healthy weight range for your height — instantly.

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Private by design.Everything happens right here in your browser. Your files are never uploaded — we never see them.

Frequently Asked Questions

How is BMI calculated? ▼

Body Mass Index is your weight in kilograms divided by your height in metres squared: BMI = kg ÷ m². Imperial values are converted to metric first (1 in = 2.54 cm, 1 lb = 0.4536 kg), so the result is identical either way.

What do the BMI categories mean? ▼

The World Health Organization ranges for adults are: Underweight below 18.5, Normal 18.5–24.9, Overweight 25–29.9, and Obese 30 and above.

What is a healthy weight for my height? ▼

A healthy weight is the range that keeps your BMI between 18.5 and 24.9. This calculator works that range out for your exact height and shows it in your chosen unit, so you can see the target span at a glance.

Is BMI accurate for everyone? ▼

BMI is a quick screening tool, not a diagnosis. It doesn't distinguish muscle from fat, so very muscular people can read as “overweight”, and it isn't designed for children, pregnant women or the elderly. Treat it as a rough guide and speak to a doctor for a full picture.

Does BMI differ for men and women? ▼

The BMI formula and adult categories are the same for men and women. Body composition does differ between sexes, which is one reason BMI is only a general screening measure rather than a precise body-fat reading.

Is my data sent anywhere? ▼

No. Every calculation runs entirely in your browser with plain JavaScript. Your height and weight are never uploaded, saved or sent anywhere — we never see them.