United Kingdom Size 40 to US: 28

United Kingdom Size 40: Corresponds to a waist size of 100 $\text{cm}$ (40 $\text{in}$), total strap length of 115 $\text{cm}$ (45.3 $\text{in}$), and recommended fit classification Relaxed / Comfortable.

US: 28: Corresponds to a waist size of 70 $\text{cm}$ (28 $\text{in}$), total strap length of 85 $\text{cm}$ (33.5 $\text{in}$), and recommended fit classification Snug / Tailored.