BMI Calculator
Calculate your Body Mass Index (BMI) and check your WHO weight category using your height and weight. Free, private, and instant in your browser.
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How to use BMI Calculator
- 1
Enter your body weight in kilograms.
- 2
Enter your height in centimeters.
- 3
Click Calculate to compute your Body Mass Index (BMI) and WHO category.
Capabilities
- Calculates adult Body Mass Index (BMI) in kg/m²
- Categorizes into WHO standards: Underweight, Normal, Overweight, Obese
- Local client-side calculation in your browser with complete privacy
How Body Mass Index (BMI) & Weight Categories Work
Body Mass Index (BMI) is a widely recognized anthropometric screening metric established by the World Health Organization (WHO) to classify body weight relative to height in adult men and women. It serves as an initial statistical reference point for evaluating weight-related health risks.
BMI is a statistical screening ratio, not a clinical diagnostic tool or medical evaluation. It does not measure subcutaneous or visceral fat distribution. For personalized health assessments, consult a qualified physician or healthcare professional.
Formula: BMI = Weight (kg) / [Height (m)]². Height is converted from centimeters to meters before squaring to produce the standard kg/m² metric.
Underweight: < 18.5 | Normal Weight: 18.5 – 24.9 | Overweight: 25.0 – 29.9 | Obese: ≥ 30.0 kg/m².
Worked Example: 70 kg and 170 cm
Suppose an individual weighs 70 kg with a height of 170 cm (1.70 meters):
Height in Meters Squared: 1.70 * 1.70 = 2.89 m²
BMI Calculation: 70 / 2.89 = 24.2 kg/m²
Resulting WHO Category: Normal Weight (18.5 – 24.9 range)
To calculate your baseline calories burned at complete rest, use BMR Calculator.
This tool operates in a sandbox directly inside your web browser. All parsing, processing, and downloads are rendered locally. Your file size, metadata, and contents never cross the network. It works completely offline.
Frequently Asked Questions
Is Body Mass Index (BMI) a direct measurement of body fat?
No. BMI is a population-level screening index based solely on the ratio of weight to height squared (kg/m²). It does not differentiate between lean muscle mass, bone density, and adipose fat tissue.
What BMI range is categorized as normal for adults?
According to the World Health Organization (WHO), a normal or healthy adult BMI falls between 18.5 and 24.9 kg/m². Values below 18.5 are classified as underweight, 25 to 29.9 as overweight, and 30 or higher as obese.
Why might BMI be less accurate for athletes and bodybuilders?
Because muscle is substantially denser than fat, muscular individuals and strength athletes often register BMI values in the overweight or obese ranges despite maintaining very low body fat percentages.
Can this calculator be used for children and teenagers?
This calculator applies the adult WHO classification standards (ages 18 and older). For children and teens aged 2 to 19, healthcare providers evaluate BMI-for-age percentiles that account for sex and active growth stages.
Are my personal health measurements kept private?
Yes. All computations execute locally in your web browser memory. Your height, weight, and health scores are never sent to external servers.