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BMI Calculator
Want to calculate your body mass index (BMI)? This tool lets you enter your height and weight to work out your BMI, a simple screening measure that helps assess weight relative to height. It's a quick and convenient way to calculate your result, with support for understanding where it falls within standard BMI categories.
All calculations are performed directly in your browser, with nothing sent to a server, so your personal measurements remain private and under your control.
BMI Calculator
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24.2
Normal weight
UnderweightNormalOverweightObese
BMI is a general screening tool, not a diagnosis. It doesn't account for muscle mass, frame size, age, sex or pregnancy — talk to a healthcare professional about what a healthy weight looks like for you.
How to use it
The BMI calculator works out your body mass index from your height and weight.
- Choose your unitsSwitch between metric (centimetres and kilograms) and imperial (feet, inches and pounds).
- Enter your height and weightThe BMI updates automatically as you type.
- Read your resultYour BMI number, its category, and where it sits on the scale are all shown together.
- Use it as a starting pointBMI is a screening measure — talk to a doctor if you have questions about your weight or health.
Good to know
Nothing is uploaded
Your height and weight are calculated in your browser and never sent anywhere.
BMI formula
BMI = weight (kg) ÷ height (m)². The imperial version multiplies by 703 instead.
Not for everyone
Standard BMI categories aren't designed for children, pregnant women, or very muscular people.
BMI categories (WHO adult reference)
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
Frequently asked questions
How is BMI calculated?
BMI = weight in kilograms ÷ (height in metres)². For imperial units, BMI = 703 × weight in pounds ÷ (height in inches)².
Is BMI accurate for everyone?
No. BMI doesn't distinguish between muscle and fat, so athletes and very muscular people can show a higher BMI without excess body fat. It also isn't designed for children, teenagers, pregnant women or older adults with reduced muscle mass.
What's a healthy BMI?
For most adults, the World Health Organization considers 18.5 to 24.9 to be within the normal weight range. This is a general guide, not an individual health assessment.
Is anything sent to a server?
No. Your height and weight are calculated locally in your browser.
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