It's a waist size, and size 29 is two feet and two inches. This change algorithm is pants size minus 7, which is what we usually call waist circumference. For example, the specification model 27, 27-7=20, that is, the waist is two feet. One inch is three centimeters, and the waist circumference of two feet two is about 74 centimeters. No matter how tall a person is, because after all, people are fat and thin. Some people are short but have a thick waist, depending on the reality. Can I understand it this way?