United Kingdom Size 54–56 to US: M (38–40)

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: M (38–40): Corresponds to a chest width of 96.5–101.6 $\text{cm}$ (38–40 $\text{in}$), neck collar girth of 39.4 $\text{cm}$ (15.5 $\text{in}$), sleeve length of 86.4 $\text{cm}$ (34 $\text{in}$), and fit style Classic Regular Fit.