US: 16-18 to United Kingdom Size 16-18

US: 16-18: Corresponds to a relaxed bust range of 105–109 $\text{cm}$ (41.3–42.9 $\text{in}$), elastic waist range of 87–92 $\text{cm}$ (34.3–36.2 $\text{in}$), and comfort drape classification Loose Lounge Fit.

United Kingdom Size 16-18: Corresponds to a relaxed bust range of 97–101 $\text{cm}$ (38.2–39.8 $\text{in}$), elastic waist range of 79–84 $\text{cm}$ (31.1–33.1 $\text{in}$), and comfort drape classification Relaxed / Comfort Drape.