BMI Calculator
Last updated: June 2, 2026Check your Body Mass Index in seconds.
BMI Calculator is a free online calculator to check your Body Mass Index in seconds. It runs entirely in your browser, so your files never leave your device — nothing is uploaded. There's no sign-up, no watermark, and it works on any modern browser on desktop or mobile.
Disclaimer: This calculator gives general estimates for informational purposes only and is not medical advice. Results vary by individual, measurement method and formula. Always consult a qualified healthcare professional before making decisions about your health, diet or fitness.
How to use BMI Calculator
The BMI Calculator works out your Body Mass Index from your height and weight and shows which World Health Organization category you fall into. Switch between metric (cm/kg) and imperial (ft/in, lb). It's free, instant and runs entirely in your browser.
Read the full guide: How to Calculate BMI: Free BMI Calculator Online
- 1Choose metric or imperial units.
- 2Enter your height and weight.
- 3Read your BMI and category instantly.
Metric & imperial
Calculate in cm/kg or feet, inches and pounds — whichever you use.
Instant result
Your BMI and WHO category update as you type, no button needed.
Private
Nothing is uploaded — it all runs on your device.
Track weight-loss progress to a healthy range
If you're dieting or training toward a goal, enter your current height and weight to see exactly where you sit against the WHO healthy band of 18.5 to 24.9. Re-check after each weigh-in and watch the number move toward normal. Because the result updates live as you type, you can also test what weight would finally drop you out of the overweight category.
Check if muscle is inflating your BMI
Lifters and athletes often read overweight or obese despite low body fat, because BMI counts only height and weight, not muscle. Use this to get your exact figure, then weigh it against the on-screen caveat: BMI ignores muscle mass and body composition. A high reading paired with visible leanness usually means the score is misleading rather than a real health concern.
Convert imperial measurements into BMI
When a clinic, gym form, or insurance questionnaire gives your height in feet and inches and weight in pounds, switch the tool to imperial and type the numbers straight in — no manual conversion to metric needed. It applies the 703 imperial formula for you and returns the same standardized BMI and category a doctor would calculate, so you can fill in forms confidently.
BMI Calculator — frequently asked questions
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². For imperial it's 703 × weight (lb) ÷ height (in)². This tool does the maths for you.
What is a healthy BMI?
The WHO considers 18.5–24.9 normal. Below 18.5 is underweight, 25–29.9 overweight, and 30+ obese.
Is BMI accurate for everyone?
BMI is a quick screening guide, not a diagnosis. It doesn't account for muscle mass, age or body composition, so very muscular people can read high.
Is this BMI calculator free?
Yes — completely free, no sign-up, and it works on any device.
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