Europe Size 56-21-150 to US: S
Cross-market adult eyewear and optical frame apparel conversion mapping 56-21-150 specifications into S.

Analyzing Size Equivalence Across Markets
Europe Size 56-21-150: Corresponds to a lens width baseline of 56 (2.2 ), bridge width of 21 , temple arm length of 150 , and fit classification Extra Wide / Oversized Frame.
US: S: Corresponds to a lens width baseline of 49 (1.93 ), bridge width of 18 , temple arm length of 140 , and fit classification Standard / Medium Frame.