Best Free BMI Calculator
Get your BMI and category instantly, in metric or imperial — free, no signup, all in your browser.
100% free
No signup
No watermark
Files processed in memory, never stored
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How it works
- Enter height and weight. Type your height and weight; the result updates live as you type.
- Pick metric or imperial. Open Advanced options to switch between cm/kg and ft·in/lb.
- Read your BMI. See the number, the category and the coloured indicator — all calculated in your browser.
About this tool
Work out your Body Mass Index the moment you type — no signup, nothing sent anywhere. Enter your height and weight and the calculator shows your BMI number, the WHO category (Underweight, Normal, Overweight or Obese) and a coloured indicator so you can see where you land at a glance. The everyday view assumes metric; flip the Advanced options unit toggle to enter feet, inches and pounds instead. Everything is computed locally on your device.
What people use it for
- Check your BMI category at a glance
- Convert between metric and imperial without a separate tool
- Track changes by re-checking after a weigh-in
- See where you fall on the Underweight–Obese scale
Frequently asked questions
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). The imperial mode converts feet, inches and pounds to metric first, so the result is identical either way.
Using the standard WHO ranges: below 18.5 is Underweight, 18.5–24.9 is Normal, 25–29.9 is Overweight and 30 or above is Obese. The coloured bar marks where your value sits.
No. Your height and weight are calculated in your browser and never uploaded, stored or logged — the page works even offline once it has loaded.
Yes. Open Advanced options and switch to Imperial; the labels change to feet/inches and pounds, and a second field appears for the inches.
BMI is a quick screening number, not a diagnosis. It does not distinguish muscle from fat, so very muscular or older people may read high or low; treat it as a rough guide.
Completely free, with no account, no watermark and no limits — it is a client-side tool with nothing to meter.
Yes. It runs in your browser, so BMI Calculator works on phones and tablets as well as desktop — there is no app to install.
No. BMI Calculator works with no signup at all; an optional free account only exists to unlock higher usage limits.
Usually just a few seconds for a typical file — BMI Calculator starts working the moment you give it your input.
Casual use is unlimited, under a generous fair-use cap that keeps it fast for everyone.