BMI Calculator - Body Mass Index
Calculate your Body Mass Index (BMI) quickly and accurately. Our calculator uses the formula validated by the World Health Organization (WHO) to assess if your weight is appropriate for your height.
Important Medical Disclaimer
This calculator is an educational and clinical decision support tool. Results DO NOT replace professional medical evaluation, laboratory tests, or clinical judgment. Always consult a qualified healthcare professional for diagnosis, treatment, and clinical decisions. Calculations are based on scientifically validated formulas but may not be applicable to all patients.
Calculate BMI
What is BMI?
Body Mass Index (BMI) is an international measure used to calculate whether a person is at their ideal weight. Developed by polymath Lambert Quetelet in the 19th century, BMI is calculated by dividing weight (in kg) by height squared (in meters).
Formula: BMI = weight / (height × height)
How to calculate BMI?
To calculate your BMI, simply divide your weight in kilograms by your height in meters squared. For example, a person weighing 70 kg and 1.75 m tall has BMI = 70 / (1.75 × 1.75) = 22.86 kg/m².
BMI Classification according to WHO
Underweight (BMI < 18.5)
May indicate malnutrition or other health problems. Consult a doctor or nutritionist.
Normal weight (BMI 18.5 - 24.9)
Congratulations! Your weight is appropriate for your height. Maintain healthy eating and exercise habits.
Overweight (BMI 25 - 29.9)
Above ideal weight. Consider adjustments in diet and increased physical activity. Seek professional guidance.
Obesity (BMI ≥ 30)
Increased risk of chronic diseases. It is essential to seek medical and nutritional support for a healthy weight loss plan.
BMI Limitations
BMI does not differentiate muscle mass from body fat. Athletes and very muscular people may have high BMI without excess fat. Elderly and children have specific tables. Always consult a healthcare professional for complete evaluation.
Frequently Asked Questions about BMI
Is BMI reliable?
BMI is a useful screening tool widely accepted by the medical community. However, it is not a definitive diagnosis. It does not consider factors such as muscle mass, bone density, fat distribution and age.
What is the ideal BMI?
According to WHO, the ideal BMI for adults is between 18.5 and 24.9 kg/m². However, ideal weight may vary according to age, sex, muscle mass and other individual factors.
Does BMI work for children?
For children and adolescents, BMI is interpreted differently, using percentile charts that consider age and sex. Consult a pediatrician for proper evaluation.
How to improve my BMI?
To achieve a healthy BMI, combine balanced diet with regular exercise. Avoid radical diets. Seek guidance from a nutritionist and physical educator for a personalized and sustainable plan.
Does BMI consider age?
The standard BMI classification is the same for adults aged 20 to 65. For the elderly, some studies suggest that a slightly higher BMI (up to 27) may be healthier. Children and adolescents use specific tables.
Related Topics
- Body fat percentage
- Waist circumference
- Waist-to-hip ratio
- Basal metabolic rate
- Ideal weight by age and height
Scientific References
- 1. World Health Organization. Obesity: preventing and managing the global epidemic. Report of a WHO consultation. World Health Organ Tech Rep Ser. 2000;894:i-xii, 1-253.
- 2. National Institutes of Health, National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. 1998.
- 3. Ministerio da Saude (Brasil). Vigilancia de Fatores de Risco e Protecao para Doencas Cronicas por Inquerito Telefonico. Brasilia: Ministerio da Saude, 2020.