BMI Calculator
Calculate your Body Mass Index from height and weight.
To find your body mass index, enter your height and weight above in either metric (cm, kg) or imperial (ft, in, lbs) units — this online BMI calculator divides your weight in kilograms by your height in metres squared (kg/m²) and shows the result with its WHO weight band. It runs entirely in your browser as you type, with no upload and no sign-up.
Read the guide: Is BMI Actually Accurate? What the Number Really Tells YouAbout the BMI Calculator
Body Mass Index (BMI) is a quick screening number that relates your weight to your height. This calculator uses the standard formula — weight in kilograms divided by the square of your height in metres (kg/m²) — and drops your result into the World Health Organization category bands so you can see at a glance whether you land in the underweight, normal, overweight, or obese range.
You can enter measurements in metric (cm and kg) or imperial (feet, inches, and pounds); the imperial inputs are converted to metric before the math, so both modes give the same result. Your BMI updates as you type. BMI is a general screening indicator, not a diagnosis, so use it as one data point rather than medical advice.
How to use it
- 1Pick your units. Tap Metric (cm, kg) or Imperial (ft, lbs) at the top.
- 2Enter height and weight. Type your height and weight into the fields (feet plus inches in imperial mode).
- 3Read your BMI. Your BMI value and its weight category appear instantly below.
Frequently asked questions
How do I calculate my BMI?+
Pick metric or imperial units, type in your height and weight, and the online calculator does the math for you: it divides weight in kilograms by height in metres squared. There is no button to press — your BMI and its category appear the moment both fields hold a number.
How is BMI calculated?+
BMI = weight (kg) ÷ height (m)². This tool computes it directly in metric; when you pick imperial, it first converts your feet and inches to metres and pounds to kilograms, which is mathematically the same as the weight (lbs) ÷ height (in)² × 703 formula.
What do the categories mean?+
This calculator uses the standard adult bands: below 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or above is obese.
Which units can I use?+
Both. Switch between metric (centimetres and kilograms) and imperial (feet, inches, and pounds) using the toggle at the top. The result is identical either way.
Is BMI accurate for everyone?+
BMI is a useful screening tool but it does not distinguish muscle from fat or account for body composition, age, or sex. Athletes and very muscular people may read as overweight while being healthy, so treat BMI as one signal, not a diagnosis.
Does it work for children?+
These category bands are for adults. Children and teenagers are assessed against age- and sex-specific percentile charts, so this calculator is not a substitute for a pediatric BMI-for-age reading.
Is my data private?+
Yes. The calculation runs entirely in your browser — nothing is uploaded, and there is no sign-up.
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