BMI Calculator

To calculate BMI online, enter your weight and height in either metric (kilograms and centimeters) or imperial (pounds and inches) units. Our free BMI calculator automatically computes your BMI using the formula: BMI = weight (kg) / [height (m)]². For imperial units, the formula is BMI = [weight (lbs) / height (inches)²] × 703. Results are instant and include your BMI category interpretation.

BMI categories according to WHO standards are: Underweight (BMI below 18.5) - may indicate malnutrition or health issues; Normal weight (BMI 18.5-24.9) - healthy weight range with lower health risks; Overweight (BMI 25-29.9) - increased risk of cardiovascular disease and diabetes; Obese (BMI 30+) - significantly higher health risks. These ranges apply to adults aged 20+. Consult healthcare providers for personalized assessment.

BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat mass, so bodybuilders and athletes with high muscle mass may show "overweight" despite being healthy. BMI may overestimate body fat in elderly people who have lost muscle mass. It doesn't account for fat distribution, bone density, or gender differences. For comprehensive health assessment, combine BMI with body fat percentage, waist circumference, and medical evaluation.

A healthy BMI range for most adults is 18.5 to 24.9, associated with lower risk of chronic diseases and mortality. To achieve healthy BMI: maintain balanced nutrition with proper calorie intake, engage in regular physical activity (150+ minutes weekly), focus on whole foods over processed items, stay hydrated, get adequate sleep, and manage stress. Gradual weight changes (0.5-1 kg per week) are healthier than rapid changes. Always consult healthcare professionals before major lifestyle modifications.

Standard adult BMI calculators are not accurate for children and teens under 20 years old because BMI changes substantially with age during growth. For youth, use BMI-for-age percentile charts that compare BMI to same-age peers. Children's BMI interpretation requires pediatrician evaluation considering growth patterns, puberty stage, and overall development. Our calculator is designed for adults; consult pediatric growth charts and healthcare providers for children's healthy weight assessment.