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BMI Calculator

Work out body mass index from height and weight, in metric or imperial, with the WHO adult category and a healthy weight range for your height.

Units

Calculated in your browser. Nothing is uploaded.

Enter your height and weight to see your BMI.

How to calculate your BMI

  1. Choose your units

    Pick Metric to enter centimetres and kilograms, or Imperial to enter feet, inches, and pounds.

  2. Enter height and weight

    Type your height and weight into the fields. The BMI appears as soon as both are valid; there is no button to press.

  3. Read the result

    The BMI shows to one decimal alongside its WHO category and the healthy weight range for your height. Click Copy BMI summary to put it on your clipboard.

Why use this tool

Metric and imperial input

Enter centimetres and kilograms, or switch to feet, inches, and pounds. Conversions happen internally and the result updates as you type.

WHO adult categories

The four standard bands sit side by side with yours highlighted: underweight, healthy weight, overweight, and obese.

Healthy range for your height

See the weight span that corresponds to a BMI of 18.5 to 24.9 at your exact height, shown in kilograms or pounds to match your units.

Honest about its limits

The result carries a plain reminder that BMI is an adult screening measure, not a diagnosis, and cannot tell muscle from fat.

Your numbers stay on your device

Height and weight are processed by the page alone. Nothing is uploaded, stored, or logged.

About this tool

This BMI calculator works out body mass index from a height and a weight: the weight in kilograms divided by the height in metres, squared. Enter your numbers in metric, or switch to imperial to use feet, inches, and pounds; the tool converts them internally and the result appears as you type, rounded to one decimal. Alongside the number you get the standard adult category and the weight span that would put a person of your height between a BMI of 18.5 and 24.9.

The categories are the WHO bands for adults: under 18.5 is underweight, 18.5 to 24.9 is considered healthy, 25 to 29.9 is overweight, and 30 or above is obese. They are worth reading with their limits in mind. BMI is a population screening measure, not an individual diagnosis. It cannot tell muscle from fat, so a muscular athlete can register as overweight, and it can understate body fat in older adults. If a result concerns you, talk it through with a health professional rather than acting on the number alone.

Height and weight are personal numbers, so the calculator keeps them personal: everything is computed on the page and nothing you type is uploaded, stored, or logged. For other everyday sums, the age calculator turns a date of birth into an exact age, and the unit converter handles standalone conversions such as pounds to kilograms or feet to centimetres.

Frequently asked questions

How is BMI calculated?
Body mass index is your weight in kilograms divided by your height in metres, squared. This calculator applies that formula as you type and rounds the result to one decimal. Imperial entries are converted to metric internally, so both unit systems give the same answer.
Can I use feet, inches, and pounds?
Yes. Switch the units toggle to Imperial to enter height as feet plus inches and weight in pounds. The healthy weight range is then shown in pounds too. Metric mode uses centimetres and kilograms.
What counts as a healthy BMI?
For adults, the WHO bands put a healthy BMI between 18.5 and 24.9. Below 18.5 is classed as underweight, 25 to 29.9 as overweight, and 30 or above as obese. The tool also shows the weight range that corresponds to the healthy band at your exact height.
Why can BMI be misleading?
BMI only relates weight to height; it cannot tell muscle from fat or say where fat is carried. Muscular people can score as overweight, and older adults can score as healthy while carrying more fat than the number suggests. It was designed for screening populations, not diagnosing individuals, so treat it as a starting point and consult a health professional about anything it raises.
Does BMI work for children?
Not with these bands. The categories here are the WHO cut-offs for adults aged 20 and over. Children and teenagers are assessed with age- and sex-specific growth percentiles instead, so use a dedicated child BMI tool or ask a health professional.
Is my height and weight kept private?
Yes. Everything is calculated in your browser. The height and weight you enter are never uploaded, stored, or logged.

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