Calculators & Time
BMI, with the caveats attached
Enter height and weight for a BMI and its category. It also shows the weight range that would put your height in the healthy band — and what the number does and does not tell you.
22.9
Healthy weight
A healthy BMI for this height is 56.7–76.3 kg.
BMI is a ratio of weight to height and nothing more. It does not distinguish muscle from fat, which is why athletes routinely land in “overweight”, and the adult categories do not apply to children, who are assessed on percentiles for their age. Treat it as one rough indicator, not a diagnosis.
- Runs in your browser
- No account required
- Free to use
How it works
Weight over height squared
Kilograms divided by metres squared. That is the whole formula, which is both why it is used everywhere and why it says so little: it has no way to distinguish muscle from fat, or where weight is carried.
The categories are for adults
The WHO bands — under 18.5, 18.5 to 25, 25 to 30, and above — describe adult populations. Children are assessed on percentiles for their age and sex instead, so the categories here do not apply to them.
Unit mistakes are caught
A height of 1.75 is metres, not centimetres, and would give a BMI in the tens of thousands. Rather than report that, the tool says the height looks wrong — the same for a weight that is obviously in pounds.
What it does
Metric and imperial
Kilograms and centimetres, or pounds with feet and inches.
The healthy range for your height
More actionable than the index itself, since it is expressed in the units you actually weigh yourself in.
Runs in your browser
No account and no upload — what you type is never sent anywhere. Analytics records that the tool was opened, never what you put into it.
Practical advice
Getting a better result
- BMI is a population measure. For an individual it is a rough screening indicator, not a diagnosis.
- Muscle is denser than fat, so athletes frequently score as overweight while being nothing of the sort.
- Waist measurement and waist-to-height ratio track health risk better than BMI for most people, and both are easy to measure at home.
Questions
Things people ask
Is BMI accurate?
It is accurate as a calculation and limited as a measure. It captures weight relative to height and nothing else — not body composition, not fat distribution, not fitness. It is useful for comparing populations and rough for assessing an individual.
Does it work for children?
The calculation does; the categories do not. Children and teenagers are assessed against percentile charts for their age and sex, because a healthy BMI changes considerably as they grow.
Why does it say my height looks wrong?
Because it was probably entered in metres rather than centimetres. 1.75 would give a nonsensical index, so the tool asks rather than reporting it.
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