US: 6-8.5 to Europe Size 21-23
Cross-market children’s socks, tights, hosiery, leg warmers, and dance tights sizing conversion mapping 6-8.5 specifications into 21-23.

Analyzing Size Equivalence Across Markets
US: 6-8.5: Corresponds to a foot length of 20 (7.9 ), matching US shoe size 13-3, and age range 84–120 months.
Europe Size 21-23: Corresponds to a foot length of 13.5 (5.3 ), matching US shoe size 5-7, and age range 12–24 months.