United Kingdom Size 16 to US: M

United Kingdom Size 16: Corresponds to a waist/hip size of 90 $\text{cm}$ (36 $\text{in}$), waist range of 81–91 $\text{cm}$ (31.9–35.8 $\text{in}$), total strap length of 100 $\text{cm}$ (39.4 $\text{in}$), and fit classification Relaxed Waist / Hip.

US: M: Corresponds to a waist/hip size of 80 $\text{cm}$ (32 $\text{in}$), waist range of 71–81 $\text{cm}$ (28–31.9 $\text{in}$), total strap length of 90 $\text{cm}$ (35.4 $\text{in}$), and fit classification Standard Waist / Hip.