United Kingdom Size 16–18 to US: XL (16–18)

United Kingdom Size 16–18: Waist contouring range of 76.2–81.3 $\text{cm}$ (30–32 $\text{in}$), full hip range of 101.6–106.7 $\text{cm}$ (40–42 $\text{in}$), style variants Briefs, High-Waist Panties & Boy Shorts, and fit classification Comfort Stretch Fit.

US: XL (16–18): Waist contouring range of 83.8–88.9 $\text{cm}$ (33–35 $\text{in}$), full hip range of 109.2–114.3 $\text{cm}$ (43–45 $\text{in}$), style variants Full Briefs, High-Waist & Boy Shorts, and fit classification Generous Full Fit.