US: 46-48 to United Kingdom Size 38-40
Cross-market men’s sleepwear conversion mapping 46-48 specifications into 38-40 for lounge pants, pajama sets, and robes.

Analyzing Sleepwear Size Equivalence Across Markets
US: 46-48: Corresponds to a relaxed chest range of 114–118 (44.9–46.5 ), elastic waist range of 100–106 (39.4–41.7 ), and fit classification Loose Lounge Fit.
United Kingdom Size 38-40: Corresponds to a relaxed chest range of 98–102 (38.6–40.2 ), elastic waist range of 84–90 (33.1–35.4 ), and fit classification Relaxed / Comfort Fit.