Here is the size chart for selecting Nike swim trunks for boys. When choosing the right size, you should consider your child's age, height, and waist measurement.
Size is often chosen based on age; however, the most important measurement is typically the hips. Additionally, you'll need to decide what fit you want for your child. For a snug fit, choose the smaller of the two sizes. Conversely, for a looser fit, opt for the larger size of the two.