BMI is a widely used measurement for adults and is applicable to individuals aged 18 and older. For children and adolescents, the interpretation of BMI differs due to variations in growth rates and body composition as they age. Pediatricians typically use growth charts and percentiles to assess children's weight and health. If you have concerns about a child's weight or BMI, it's best to consult with a healthcare professional who specializes in pediatric care for accurate evaluation and guidance.