BMI Calculator
Calculate adult body mass index from height and weight, then understand what the result can—and cannot—tell you about body composition.
Healthy range. BMI is a population-level screening measure and does not distinguish muscle mass from body fat.
How BMI is calculated
BMI divides weight in kilograms by height in meters squared. For example, a person who weighs 75 kg and is 1.78 m tall has a BMI of 75 ÷ 1.78² = 23.7.
Adult BMI categories
Categories are screening references, not diagnoses. Age, pregnancy, ethnicity, muscle mass, and individual health history can change how a clinician interprets the same result.
When BMI can be misleading
BMI cannot tell whether weight comes from fat, muscle, bone, or fluid. Strength athletes may have a high BMI with relatively low body fat, while someone can have a BMI in the standard range and still carry more abdominal fat than expected.
Use waist measurements, consistent progress photos, performance, and a qualified professional's assessment when you need more context than height and weight provide.
Related body composition tools
Estimate body fat from a photo, calculate fat-free mass index, or review the body fat percentage chart.