United Kingdom Size 54–56 to US: XL (46–48)

United Kingdom Size 54–56: Corresponds to a chest width of 137.2–142.2 $\text{cm}$ (54–56 $\text{in}$), neck collar girth of 49.5 $\text{cm}$ (19.5 $\text{in}$), sleeve length of 96.5 $\text{cm}$ (38 $\text{in}$), and fit style Big & Tall Fit.

US: XL (46–48): Corresponds to a chest width of 116.8–121.9 $\text{cm}$ (46–48 $\text{in}$), neck collar girth of 44.5 $\text{cm}$ (17.5 $\text{in}$), sleeve length of 91.4 $\text{cm}$ (36 $\text{in}$), and fit style Generous Full Fit.