US: 8.5–10.5 to United Kingdom Size 5.5–7.5
Cross-market men’s sock conversion mapping 8.5–10.5 specifications into 5.5–7.5.

Analyzing Sock Size Equivalence Across Markets
US: 8.5–10.5: 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.
United Kingdom Size 5.5–7.5: Corresponds to a US shoe size range of 6–8, foot length of 24–26 (9.4–10.2 ), and fit classification Standard Athletic / Form Fit.