US: 5XL to United Kingdom Size 18

US: 5XL: Corresponds to a waist/hip size of 110 $\text{cm}$ (44 $\text{in}$), waist range of 102–112 $\text{cm}$ (40.2–44.1 $\text{in}$), total strap length of 120 $\text{cm}$ (47.2 $\text{in}$), and fit classification Extended Plus.

United Kingdom Size 18: Corresponds to a waist/hip size of 95 $\text{cm}$ (38 $\text{in}$), waist range of 86–97 $\text{cm}$ (33.9–38.2 $\text{in}$), total strap length of 105 $\text{cm}$ (41.3 $\text{in}$), and fit classification Relaxed Waist / Hip.