US: 4-6 to United Kingdom Size 12-14
Cross-market women’s sleepwear conversion mapping 4-6 specifications into 12-14 for nightgowns, pajama sets, and sleep shirts.

Analyzing Women’s Sleepwear Equivalence Across Markets
US: 4-6: Corresponds to a relaxed bust range of 84–88 (33.1–34.6 ), elastic waist range of 66–70 (26–27.6 ), and comfort drape classification Relaxed / Comfort Drape.
United Kingdom Size 12-14: Corresponds to a relaxed bust range of 90–94 (35.4–37 ), elastic waist range of 72–76 (28.3–29.9 ), and comfort drape classification Relaxed / Comfort Drape.