In the UK, a size 18 typically corresponds to a bust measurement of 44 inches, a waist measurement of 36 inches, and hip measurement of 46 inches. This size is often considered part of the plus-size range in women's clothing, catering to those who require larger fit options. Clothing labeled as UK Size 18 is designed to provide a comfortable fit for individuals with these measurements. Brands may vary in their sizing, so it's advisable to check specific size charts when shopping, as some may run larger or smaller than standard sizing.