US: 11–13 to United Kingdom Size 10.5–12.5
Cross-market men’s sock conversion mapping 11–13 specifications into 10.5–12.5.

Analyzing Sock Size Equivalence Across Markets
US: 11–13: Corresponds to a US shoe size range of 11–13, foot length of 28.5–30 (11.2–11.8 ), and fit classification Relaxed / Comfort Stretch.
United Kingdom Size 10.5–12.5: Corresponds to a US shoe size range of 11–13, foot length of 28.5–30 (11.2–11.8 ), and fit classification Relaxed / Comfort Stretch.
Other Conversions to United Kingdom Size 10.5–12.5
US: 4–5.5 → uk-10-5-12-54–5.5 to uk-10-5-12-5
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US: 6–8 → uk-10-5-12-56–8 to uk-10-5-12-5
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US: 8.5–10.5 → uk-10-5-12-58.5–10.5 to uk-10-5-12-5
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US: 11–13 → uk-10-5-12-511–13 to uk-10-5-12-5
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US: 13.5–15 → uk-10-5-12-513.5–15 to uk-10-5-12-5
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US: 15.5–18 → uk-10-5-12-515.5–18 to uk-10-5-12-5
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