Europe Size 15 to US: M
Cross-market adult bracelet and cuff apparel conversion mapping 15 specifications into M.

Analyzing Size Equivalence Across Markets
Europe Size 15: Corresponds to a wrist circumference baseline of 14 (5.5 ), bracelet length of 15 (5.9 ), and fit classification Snug / Compact.
US: M: Corresponds to a wrist circumference baseline of 16.5 (6.5 ), bracelet length of 18 (7.1 ), and fit classification Standard / Regular.