How BMI is calculated
Body mass index divides your weight by the square of your height: kg/m² in metric units, or 703 × lb/in² in imperial units. The result places you in one of four standard adult categories: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (30 and above).
What a healthy range means
The healthy weight range shown is the weight that would put your BMI between 18.5 and 24.9 at your current height. It's a population-level guideline: athletic people often sit above it because muscle weighs more than fat, and it doesn't account for age, sex, or body composition.
Limitations worth knowing
BMI is a quick screening tool, not a medical assessment. It can't tell muscle from fat, doesn't reflect where fat is carried, and the standard cutoffs fit some populations better than others. If your result concerns you, waist measurement and a conversation with a clinician tell you far more.