The BMI Calculator computes your Body Mass Index instantly using your weight and height, supporting both metric (kg/cm) and imperial (lbs/inches) units. BMI is a widely used screening tool that estimates whether you're underweight, normal weight, overweight, or obese based on your height-to-weight ratio. Whether you're tracking your fitness progress, preparing for a medical appointment, or simply curious about your health metrics, this calculator gives you immediate results with clear category guidelines. All calculations are performed locally in your browser.
Choose between Metric (kilograms and centimeters) or Imperial (pounds and inches) using the toggle buttons. If you're unsure of your measurements in one system, you can switch to the other. The calculator adjusts the input labels and formula automatically.
Input your weight and height in the selected units. For metric, enter weight in kilograms and height in centimeters. For imperial, enter weight in pounds and height in total inches (e.g., 5 feet 9 inches = 69 inches). Use current, accurate measurements for the most meaningful result.
Press the Calculate BMI button to compute your Body Mass Index. The formula for metric is weight(kg) ÷ height(m)², and for imperial it's (weight(lbs) ÷ height(in)²) × 703. Your result will be rounded to one decimal place for clarity.
Your BMI result is displayed with a color-coded category label. Check the reference chart below to see where your BMI falls: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), or Obese (30 and above). Remember that BMI is a screening tool, not a diagnostic measure.
BMI (Body Mass Index) is a numerical value calculated from your weight and height. The metric formula is: BMI = weight (kg) ÷ height (m)². For imperial units: BMI = (weight (lbs) ÷ height (in)²) × 703. BMI was developed by Belgian mathematician Adolphe Quetelet in the 1830s and is widely used by healthcare providers as a simple screening tool for weight categories.
According to the World Health Organization (WHO), a healthy BMI falls between 18.5 and 24.9. Below 18.5 is classified as underweight, 25–29.9 as overweight, and 30 or above as obese. These ranges apply to adults over 20 years old. Children and teenagers use age-specific BMI percentile charts instead of fixed ranges.
BMI has limitations for athletes and people with high muscle mass. Since muscle weighs more than fat by volume, muscular individuals may have a high BMI while being perfectly healthy. BMI doesn't distinguish between muscle mass and fat mass. For these individuals, alternative measures like waist circumference, body fat percentage, or waist-to-hip ratio provide better health assessments.
Standard adult BMI categories are the same regardless of age or gender. However, BMI interpretation can vary: women typically have more body fat than men at the same BMI, and older adults tend to have more body fat than younger adults. Some health organizations suggest slightly different healthy ranges for people over 65 (20–25 instead of 18.5–24.9).
No, BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, body composition, age, gender, or ethnicity. A comprehensive health assessment should include additional measures such as waist circumference, blood pressure, cholesterol levels, blood sugar, and physical fitness. Always consult a healthcare professional for personalized health advice.