BMI calculator
Free BMI calculator with instant, accurate results. Enter height and weight in metric or imperial to find your body mass index and WHO weight category.
How to use
- Choose your units. Pick metric (cm, kg) or imperial (ft, in, lb) so you can enter measurements the way you already know them.
- Enter your height. Type your height in centimetres, or in feet and inches if you selected imperial units.
- Enter your weight. Add your weight in kilograms or pounds to match your chosen unit system.
- Read your result. See your BMI number instantly, along with the WHO category: underweight, normal, overweight, or obese.
Features
- Metric and imperial. Works with cm and kg or feet, inches, and pounds, with no manual unit conversion needed.
- Instant WHO category. Maps your number to the standard World Health Organization bands so you know where it falls at a glance.
- Accurate, transparent math. Uses the standard BMI formula (weight divided by height squared) so the result is consistent and verifiable.
- No sign-up or limits. Calculate as many times as you like, completely free, with nothing to install.
When to use it
- Checking where your weight falls relative to your height before a routine health check-up.
- Tracking your BMI over time as you adjust diet or exercise habits.
- Quickly converting between metric and imperial without doing the math by hand.
- Getting a baseline number to discuss with a doctor, dietitian, or trainer.
- Comparing readings for family members using whichever units they prefer.
Is it private?
Everything runs entirely in your browser, and nothing you enter is ever sent to a server.
Frequently asked questions
Is this BMI calculator free?
Yes, it is completely free with no sign-up, no limits, and no install required.
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared. For imperial inputs, the tool converts feet, inches, and pounds first, then applies the same formula.
What do the weight categories mean?
Using WHO bands for adults, a BMI under 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI an accurate measure of health?
BMI is a useful general screening indicator, but it does not account for muscle mass, body composition, age, or sex. It is information only, not a diagnosis or medical advice.
Does BMI work for everyone?
The standard categories apply to most adults. They are less reliable for athletes, pregnant people, older adults, and children, so consult a healthcare professional for personal guidance.
Do you store my height and weight?
No. Everything is calculated in your browser and nothing you enter is sent to or saved on a server.
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