US: 4-6 to United Kingdom Size 6

US: 4-6: Waist range of 65–69 $\text{cm}$ (25.6–27.2 $\text{in}$), hip range of 91–95 $\text{cm}$ (35.8–37.4 $\text{in}$), lengths (Mini/Midi/Maxi): 43.5/76.5/101.5 $\text{cm}$ (17.1/30.1/40 $\text{in}$), and fit style Fitted Waist / A-Line & Straight.

United Kingdom Size 6: Waist range of 60–64 $\text{cm}$ (23.6–25.2 $\text{in}$), hip range of 86–90 $\text{cm}$ (33.9–35.4 $\text{in}$), lengths (Mini/Midi/Maxi): 42/75/100 $\text{cm}$ (16.5/29.5/39.4 $\text{in}$), and fit style Fitted Waist / A-Line & Straight.