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BMI Calculator

Work out your Body Mass Index, see which category it falls in, and a healthy weight range for your height. Everything runs locally in your browser.

New to this? Read the BMI Calculator guide →

Your BMI

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BMI is a general screening measure and doesn't account for muscle, age, or body composition. Not medical advice.

How to use the BMI calculator

  1. Enter your height and weight in metric or imperial units.
  2. Read your BMI and the category it falls into.
  3. Everything is calculated in your browser; nothing is stored or uploaded.

What BMI measures

Body Mass Index is your weight divided by your height squared (kg / m²). It is a quick, standardised way to relate weight to height across a population. The widely used categories are:

What BMI can't tell you

BMI is a screening tool, not a diagnosis. It does not distinguish muscle from fat, so very muscular people can read as "overweight" while the number can understate body fat in others. It is also less reliable for older adults, children, and during pregnancy, and it says nothing about where fat is carried. Treat it as one rough indicator and talk to a healthcare professional for a fuller picture. For a deeper look, the companion article "Is BMI accurate?" is on the way.

Where you'd use this

A quick population-level screening number, useful as one input among several — and worth understanding the limits of before drawing conclusions from it.

For example: Someone 1.78m and 84kg gets a BMI of 26.5, nominally "overweight". If that person is a rower carrying substantial muscle, waist-to-height ratio is the more informative number — which is why BMI is a starting point, not a diagnosis.

Frequently asked questions

How is BMI calculated?

BMI is your weight in kilograms divided by your height in metres squared (kg/m²). The calculator handles both metric and imperial units for you.

What is a healthy BMI range?

For most adults, 18.5–24.9 is considered healthy, 25–29.9 overweight and 30 or more obese. BMI is a general screen, not a diagnosis, and does not account for muscle mass.

Is my health data uploaded?

No. Your height and weight are used only in your browser and never transmitted.

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