BMI Calculator

Calculate your BMI from height and weight in metric or imperial units, see your WHO weight category and the healthy weight range for your height.

The BMI Calculator works out your Body Mass Index from height and weight, accepting either metric (kg and cm) or imperial (lb, ft and in) units. Alongside the number, it shows which WHO weight category you fall into — underweight, healthy, overweight or obese — and the healthy weight range for your exact height.

It's a quick reference for tracking weight trends over time or getting a general sense of where you stand, calculated instantly with no data leaving your browser. The calculator works equally well as a bmi calculator kg and cm or in pounds and inches, so there's no need to convert units yourself beforehand.

How to use the BMI Calculator

  1. Select metric or imperial units depending on how you know your height and weight.
  2. Enter your height in centimetres, or feet and inches.
  3. Enter your weight in kilograms, or pounds.
  4. View your calculated BMI value along with its WHO category.
  5. Check the healthy weight range shown for your specific height.

Why use this tool

Both unit systems supported

Metric and imperial entry are both available, so there's no need to convert kg to lb or cm to inches beforehand.

WHO category shown alongside the number

The raw BMI figure is paired with its underweight, healthy, overweight or obese classification for immediate context.

Healthy weight range for your height

Rather than just a single number, the calculator shows the full weight range considered healthy at your specific height.

Instant, private calculation

Height and weight figures are processed locally in the browser and are never transmitted or stored.

Common use cases

How BMI is calculated

BMI equals weight in kilograms divided by height in metres squared. The calculator performs this conversion automatically regardless of whether you entered metric or imperial values, so the underlying formula is always consistent.

WHO weight categories

The World Health Organization classifies a BMI below 18.5 as underweight, 18.5–24.9 as healthy weight, 25–29.9 as overweight, and 30 or above as obese. These bands are the same ones used by most public health services worldwide.

Limitations of BMI

BMI is a population screening tool, not a diagnosis. It does not distinguish muscle from fat, so athletes and very muscular people often score higher than their body composition would suggest, and it doesn't account for age, sex, or where fat is distributed on the body.

Using BMI alongside other measures

For a fuller picture, BMI is often considered together with waist circumference, body fat percentage or a doctor's assessment, especially near the boundaries between categories.

Frequently asked questions

What is a healthy BMI range?

The WHO classifies 18.5–24.9 as healthy, below 18.5 as underweight, 25–29.9 as overweight and 30 or above as obese.

Is BMI accurate for everyone?

It is a population screening measure, not a diagnosis. Muscular athletes often score high despite low body fat, and it does not account for age, sex or fat distribution.

Is BMI Calculator free to use?

Yes. BMI Calculator on Klipza is completely free with no account, no subscription and no watermark on your files, and there is no daily usage limit.

Are my files safe when using BMI Calculator?

Processing happens locally in your browser wherever technically possible, so your files are not uploaded to a server, stored or shared with third parties.

Does BMI Calculator work on mobile phones?

Yes. It is fully responsive and runs in any modern browser on Android, iPhone, iPad, Windows and macOS — nothing to install.