US: 4–5.5 to United Kingdom Size 8–10
Cross-market men’s sock conversion mapping 4–5.5 specifications into 8–10.

Analyzing Sock Size Equivalence Across Markets
US: 4–5.5: Corresponds to a US shoe size range of 4–5.5, foot length of 22–23.5 (8.7–9.3 ), and fit classification Snug / Compact Fit.
United Kingdom Size 8–10: Corresponds to a US shoe size range of 8.5–10.5, foot length of 26.5–28 (10.4–11 ), and fit classification Standard Regular Fit.