BMI Calculator
Enter your height and weight to see your body mass index, WHO category, and healthy weight range instantly.
Enter your height and weight to see your BMI.
Based on WHO adult BMI categories. Processed on your device — nothing is sent anywhere.
How it works
- Choose metric (cm and kg) or imperial (feet, inches and pounds) units.
- Enter your height and weight — the result updates as you type.
- Read your BMI, WHO category, and the healthy weight range for your height below.
Frequently asked questions
- How is BMI calculated?
- BMI is your weight in kilograms divided by your height in meters squared. With imperial units the formula is weight in pounds divided by height in inches squared, multiplied by 703. Both give the same result.
- What do the BMI categories mean?
- The World Health Organization defines four adult ranges: under 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight, and 30 or above is obese. These cut-offs apply to adults aged 20 and over.
- Is BMI accurate for everyone?
- BMI is a useful screening measure but it does not distinguish muscle from fat, so athletes can score high while being lean. It is also less reliable for children, pregnant women, and the elderly. Treat it as a starting point, not a diagnosis.
- How is the healthy weight range for my height worked out?
- The calculator inverts the BMI formula: it multiplies your height in meters squared by 18.5 and by 24.9, the boundaries of the WHO normal range. The result is the span of weights that would place you in the normal category — for someone 175 cm tall, roughly 57 to 76 kg.
- Is my height and weight data stored or sent anywhere?
- No. The calculation runs entirely in your browser with no network requests, so nothing you enter is uploaded, logged, or saved. Health-related data never leaves your device, and the calculator keeps working even if you go offline after the page loads.
About this tool
This BMI calculator computes your body mass index from height and weight, assigns the World Health Organization category, and shows the weight range that would count as normal for your height. It accepts metric or imperial units, converts between them correctly, and updates the result live as you type — no signup, no email, no steps beyond entering two numbers.
The math is the standard WHO definition: weight in kilograms divided by height in meters squared, with the imperial form using the familiar ×703 factor. Categories follow the adult cut-offs used by health services worldwide — under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. The healthy range shown underneath is those same boundaries solved for weight at your height, which turns an abstract index into a concrete number of kilograms or pounds you can actually reason about.
Everything runs client-side in your browser. Height and weight are health data, and this tool treats them accordingly: there are no network requests, nothing is stored, and no analytics event carries your measurements. You can open the page, disconnect from the internet, and still use the calculator.
BMI is best understood as a screening tool rather than a verdict. It correlates with body fat across populations but says nothing about your individual composition — a muscular 90 kg athlete and a sedentary person of the same height and weight get the same score. It also uses different reference curves for children and teens, and it is not meaningful during pregnancy. If your result sits near a category boundary, a waist measurement or a conversation with a doctor tells you far more than the second decimal place of the index. Used with those caveats, checking BMI a few times a year is a reasonable, low-effort way to track long-term weight trends.