BMI calculator
Calculate your Body Mass Index with metric or imperial units and see the WHO weight category. Runs entirely in your browser — no data is uploaded.
About this tool
Body Mass Index relates weight to height and is used worldwide as a first-pass screening number. Enter your weight and height in metric (kilograms and centimeters) or imperial (pounds and inches) units and this calculator shows your BMI together with the standard WHO categories: underweight below 18.5, normal weight 18.5–24.9, overweight 25–29.9 and obesity at 30 and above. Both unit systems use the same formula, so they agree apart from rounding.
Treat the result as general information, not a diagnosis. BMI cannot distinguish muscle from fat, so very muscular people can score high without excess body fat, and it does not account for age, pregnancy or bone density. Questions about your own health belong with a qualified healthcare professional. Your numbers are calculated locally in your browser and never leave the page.
How to use BMI calculator
- Choose Metric (kg, cm) or Imperial (lb, in) units.
- Enter your weight and height.
- Run the calculation to see your BMI, the WHO category and general notes.
Keep the original files and inspect the exported result before publishing or sharing it.
Frequently asked questions
What is BMI?
Body Mass Index estimates body fat from weight and height: weight in kilograms divided by height in meters squared. In imperial units the formula is 703 × weight(lb) ÷ height(in)².
What are the WHO categories?
Underweight is below 18.5, normal weight is 18.5–24.9, overweight is 25–29.9, and obesity is 30 and above.
Do metric and imperial give the same result?
Yes, apart from tiny rounding differences — both use the same underlying formula with converted units.
Is BMI accurate for athletes or muscular people?
Not always. BMI can't tell muscle from fat, so very muscular people may score high without excess body fat. It also doesn't account for age, pregnancy or bone density.
Is my data uploaded anywhere?
No. The calculation runs locally in your browser. Nothing you type leaves this page.
Is this medical advice?
No. This tool provides general information only. Talk to a qualified healthcare professional about your health.
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