BMI Calculator
Calculate your BMI instantly. Get your body mass index category, healthy weight range, and personalized recommendations.
BMI is a screening tool, not a diagnosis. Muscle mass, bone density, and fat distribution are not captured.
Monitor your health metrics with CalRay
Your BMI is just one data point. Use CalRay to track weight, nutrition, and progress over time.
Common Questions
What is a healthy BMI?
For most adults, a healthy BMI is between 18.5 and 24.9. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese. These ranges apply to adults 18–65 and may vary for older adults or specific populations.
How is BMI calculated?
BMI is calculated by dividing your weight in kilograms by your height in meters squared: BMI = kg / m². For example, 75 kg and 1.75 m gives 75 / (1.75 × 1.75) = 24.5.
What are BMI limitations?
BMI does not distinguish between muscle and fat, so very muscular people may have a high BMI despite low body fat. It also does not account for fat distribution, bone density, or individual metabolic health.
Is BMI accurate for athletes?
BMI often overestimates body fat in athletes because muscle is denser than fat. Athletes may have a BMI in the overweight range while having very low body fat. Waist circumference and body composition tests are better alternatives.
Does BMI change with age?
BMI categories are the same across adult ages, but interpretation can shift. Older adults may have slightly higher healthy ranges due to natural muscle loss. For children and teens, BMI is compared to age- and sex-specific percentiles.