The days of buying women's clothing by size are gone. Each manufacturer has a different set of measurements and corresponding sizes. The reasons behind this development are also diverse among the designers and makers of clothes. For example, in order to charge more for their designs, some clothing companies will pretend that a size 12 is a "plus-size," for the purpose of charging more for it (as though accommodating a 38-inch bust were going to require several yards more fabric...). Size 10 used to be the ideal, and now some clothes-designers are calling garments with 36-24-36 a size "4". Others are calling 40-28-40 a size 18, which is patently ridiculous. One company comes to mind, and that is J. Peterman, a big offender in this department, which sells what used to be marketed as size 12 as an "18", causing their 18s to consistently sell-out immediately, because the average sized woman in the United States is what used to be a size 12. So how could a size 12 be labelled "plus" by any honest broker? Plus sizes, when they were first conceived by the industry, begin after what was traditionally called a size 18 or 20. Size 12 is nowhere near "plus" in any realistic, honest sizing-system. And when I wore something from their store in a fashion-show, Chico's, to make women feel good about themselves, labelled their sizes "1" --"3" for normal-sized women, up to and including what other clothing companies were defining as size 16.
The vast gaps between particular size-labels is so wide that you are better-off disregarding them altogether, and to instead look at the measurements that each company's "sizes" are supposed to represent. The only numbers that matter now are the circumferences of your bust, waist (located one inch above your navel), and hips.
©M-J de Mesterton 2010