4t Underwear Boy Market Report: Sales Volume, Market Share, Leading Brands & Market Trends

Hanes is the best-performing 4t underwear boy brand in July 2026, moving 16,000 units across 5 ASINs for 61.5% of Top 10 volume. Nike follows with 2,000 units (7.7%), ahead of MooMoo Baby on 2,000 units (7.7%).

With 6 brands splitting the Top 10 and 76.9% of volume sitting with three of them, this is a concentrated shelf — the leaders hold multiple listings or one very high-velocity ASIN, so a new entrant competes against established review moats rather than an open field. Average selling prices among the leaders run from $12.75 to $32.99, which frames the price band a competing listing has to justify.

Based on July 2026 data, this shortlist surfaces the two kinds of ASIN worth keeping an eye on — the ones that just broke into the Top 10, and the ones growing fastest month over month. Specifically, 2 ASINs forced its way in: B0B7KGP5T6 booked 2K units at $25.99, with ▲ 100.0% MoM change. On the growth side, B0CWS9CXLP leads positive momentum with ▲ 200.0% MoM growth on 600 units.

The two signals carry different weight. A fresh entrant means share has already changed hands — an incumbent gave up its place to make room, so any competitive set drawn up a month ago is now out of date. A steep growth rate works as the earlier warning: it marks demand that is still compounding, usually a month or two before the ranking catches up to it.