US: 30 to United Kingdom Size 36

US: 30: Corresponds to a waist size of 75 $\text{cm}$ (30 $\text{in}$), total strap length of 90 $\text{cm}$ (35.4 $\text{in}$), and recommended fit classification Standard / Regular.

United Kingdom Size 36: Corresponds to a waist size of 90 $\text{cm}$ (36 $\text{in}$), total strap length of 105 $\text{cm}$ (41.3 $\text{in}$), and recommended fit classification Standard / Regular.