The size 12 in jeans can vary depending on the brand and style. To determine the correct size, it is recommended to refer to the size chart provided by the manufacturer. For example, according to the size chart provided by True Religion, a size 12 corresponds to a waist measurement of 31.5 inches and a hip measurement of 39 inches. Similarly, according to the size chart provided by Silver Jeans Co. , a size 12 corresponds to a waist measurement of 32.5 inches and a hip measurement of 39.5 inches. It is important to note that sizes may vary from brand to brand and style to style, so it is always best to refer to the specific size chart for the brand and style of jeans you are interested in purchasing.