US: 38-40 to United Kingdom Size 50-52

US: 38-40: Corresponds to a relaxed chest range of 98–102 $\text{cm}$ (38.6–40.2 $\text{in}$), elastic waist range of 84–90 $\text{cm}$ (33.1–35.4 $\text{in}$), and fit classification Relaxed / Comfort Fit.

United Kingdom Size 50-52: Corresponds to a relaxed chest range of 122–126 $\text{cm}$ (48–49.6 $\text{in}$), elastic waist range of 108–114 $\text{cm}$ (42.5–44.9 $\text{in}$), and fit classification Loose Lounge Fit.