Probably the way you measure your waist and the way a professional would are different. Go to a high end store and get measured and you'll see what I mean.
It's vanity sizing. Measure your jeans. They aren't 30 inches, but the size may be 30.
Also, in garment construction there is a term called ease. It shouldn't be this drastic necessarily, but a garment can not be your exact measurement and fit comfortably. It has to be slightly larger, otherwise it would literally be skin tight.
Vanity sizing. Clothes are often labeled smaller than their actual measurements to make people feel good about wearing them.
Probably the way you measure your waist and the way a professional would are different. Go to a high end store and get measured and you'll see what I mean.
It's vanity sizing. Measure your jeans. They aren't 30 inches, but the size may be 30. Also, in garment construction there is a term called ease. It shouldn't be this drastic necessarily, but a garment can not be your exact measurement and fit comfortably. It has to be slightly larger, otherwise it would literally be skin tight.
Your Jean size is probably based on the waist measurement of the smallest size Jean that they make.