BMI Calculator
Body mass index in metric or imperial, with the caveats.
BMI Calculator computes body mass index from height and weight in metric or imperial units and places the result on the World Health Organization scale. BMI is a rough population-level screening number, not a diagnosis — the page explains where it misleads. Nothing you enter is stored or transmitted.
Loading BMI Calculator…
Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.
This is a calculation tool, not medical advice. The result is an estimate from a published formula and cannot account for your individual circumstances. Talk to a healthcare professional about anything that matters.
How to use BMI Calculator
- Choose metric or imperial units.
- Enter your height and weight.
- Read the BMI value, the WHO category, and the limitations note.
Questions about BMI Calculator
Where does BMI go wrong?
It cannot tell muscle from fat, so athletes are routinely classified as overweight. It ignores fat distribution, which matters more for cardiovascular risk than total mass. It was derived from European populations and reads differently across ethnic groups — several health bodies use a lower overweight threshold for people of South Asian descent. And it is not valid for children, pregnancy, or older adults who have lost muscle.
What are the WHO categories?
Under 18.5 underweight; 18.5-24.9 normal range; 25.0-29.9 overweight; 30.0 and above obese, subdivided at 35 and 40. These are population screening bands, not personal targets.
Is this medical advice?
No. It is arithmetic. A number from this page cannot diagnose anything or tell you what to do about your health — talk to a clinician who can look at the rest of the picture.
Which units does the imperial mode take?
Feet and inches for height, pounds for weight. There is no stones-and-pounds field, so convert first if that is how you weigh yourself — 11 stone 4 is 158 pounds. Metric mode takes centimetres and kilograms.
Is it safe to enter my height and weight here?
Yes. Both numbers are read by JavaScript inside your own tab and used only to fill in the formula. There is no account, no upload and nothing written to storage, so closing the page discards them.
Is BMI Calculator really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use BMI Calculator?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.