United Kingdom Size 26–28 to US: S (28–30)

United Kingdom Size 26–28: Corresponds to a waist stretch range of 66–71 $\text{cm}$ (26–28 $\text{in}$), hip circumference of 84 $\text{cm}$ (33 $\text{in}$), thigh clearance of 48 $\text{cm}$ (18.9 $\text{in}$), and fit style Briefs, Trunks & Boxer Briefs.

US: S (28–30): Corresponds to a waist stretch range of 71–76 $\text{cm}$ (28–30 $\text{in}$), hip circumference of 89 $\text{cm}$ (35 $\text{in}$), thigh clearance of 51 $\text{cm}$ (20.1 $\text{in}$), and fit style Briefs, Boxers & Boxer Briefs.