United Kingdom Size 16-18 to US: 20-22

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.

US: 20-22: Corresponds to a relaxed bust range of 113–117 $\text{cm}$ (44.5–46.1 $\text{in}$), elastic waist range of 95–100 $\text{cm}$ (37.4–39.4 $\text{in}$), and comfort drape classification Loose Lounge Fit.