US: 42-44 to United Kingdom Size 38-40
Cross-market men’s sleepwear conversion mapping 42-44 specifications into 38-40 for lounge pants, pajama sets, and robes.

Analyzing Sleepwear Size Equivalence Across Markets
US: 42-44: Corresponds to a relaxed chest range of 106–110 (41.7–43.3 ), elastic waist range of 92–98 (36.2–38.6 ), and fit classification Relaxed / Comfort 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.