BMI Calculator Imperial & Metric

Calculate your Body Mass Index (BMI) instantly using metric (cm, kg) or imperial (feet, inches, lbs) units. Get your official health category and healthy weight range with zero data leaving your device.

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BMI calculator with pounds, feet and inches

For adults only. BMI is a screening tool, not medical advice or a diagnosis.

Switch to Imperial to enter pounds, feet and inches, or use Metric for kilograms and centimeters. For adults, BMI equals weight in kilograms divided by height in meters squared; the US customary formula is 703 × pounds ÷ inches squared. The result is a screening measure, not a diagnosis.

Adult BMI categories

Under 18.5: underweight. 18.5 to under 25: healthy weight. 25 to under 30: overweight. 30 or higher: obesity. The calculator shows a weight range based on the adult 18.5–24.9 interval.

Age and sex considerations

Adult categories are generally used from age 20. Children and teens need age- and sex-specific BMI percentiles. BMI does not distinguish muscle from fat or capture every health risk; discuss concerns with a clinician.

How It Works

Body Mass Index (BMI) is a standardized screening metric established by the World Health Organization (WHO) to categorize body mass based on height and weight. Pexlii calculates your BMI locally on your device without sending any personal health or body measurements across the internet. When you select the Metric tab, the tool uses the standard formula: weight in kilograms divided by the square of height in meters (kg/m²). When you select the Imperial tab, your height in feet and inches is converted to total inches and multiplied by the standard imperial conversion factor of 703: (weight in lbs / height in inches²) × 703. The calculator maps your result to official WHO weight classifications: Underweight (< 18.5), Normal Weight (18.5–24.9), Overweight (25–29.9), and Obesity (30+). It also computes your personalized healthy weight range based on your exact height. Every calculation happens instantly in your browser memory, ensuring complete confidentiality for your personal health numbers.

🔒 Your files and entered content are processed on this device and are not uploaded by this tool. Pexlii also loads Google Analytics for usage measurement; tool events include the tool name, category, and action type, not your files or entered content.