Only Trusted BMI Calculator
v1Height and weight in, BMI and healthy range out.
Free · No uploads · On-deviceEnter your height and weight.
Nothing calculated yet. Everything stays on this page.
How it works
Weight over height squared
BMI is weight in kilograms divided by height in metres squared. Inches are converted at 2.54 centimetres each and pounds at 0.45359237 kilograms each before the formula runs. The result is shown to one decimal place.
The healthy range is the weight range that puts BMI between 18.5 and 24.9 for your height: 18.5 times height squared, up to 24.9 times height squared. The bands shown are the commonly used adult bands: under 18.5 underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, 30 and above obese.
Guide
Reading the number honestly
- It is a screen, not a verdict: BMI cannot tell muscle from fat. A muscular person can score overweight while healthy.
- Measure cleanly: weigh in the morning, after the bathroom, before eating, in light clothes. Measure height barefoot, standing straight.
- Watch the trend, not one reading: one number moves with water, food and the time of day. The same measurement weekly tells you more.
- Children are different: this tool uses adult bands only. Children need age and sex percentiles from a clinician.
Questions
Is BMI an accurate health measure?
It is a screening number, not a diagnosis. It does not tell muscle apart from fat, so athletes can score high while healthy, and it does not account for age, sex or pregnancy. Use it as a rough guide, and talk to a clinician for anything that matters.
What counts as a healthy BMI?
For adults, the commonly used bands are under 18.5 underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, and 30 and above obese. These are population bands, not personal targets.
Does this work for children?
No. Children are assessed against age and sex percentiles, not adult bands. This calculator uses the adult formula and bands only.
Do my height and weight leave this page?
No. The calculation runs in your browser, on your device. Nothing is uploaded, saved or sent anywhere.