As for the size of the problem is not uniform, this is indeed true, there are still some bra is not divided into cup level, only 32/34/36/38 and so on, this is basically a kind of chest strap Way to tie the chest, of course, this is an extremely non-standard annotation. There are still some brands on the market logo is 32A BCD 34A B ... or 70A BCD 75A B .... For Chinese, it is generally more common in centimeters, so 70 75 80 85 .... This logo is more suitable for domestic. With the development of the Internet, more and more online shopping crowd, the more businesses will do the following online logo, which is our definition of the size of the traditional underwear. In fact, 32,34,36 those who originally logo the United States fashion coat a little out of date, come back to life. Exaggerated metaphor, of course, too subtly adjust the underwear, our modified underwear is to adjust the functionality of underwear into the design of ordinary underwear, the measured upper and lower chest number after subtracting the base 10 , For each increase of more than 2.5cm to increase one level, so we are in accordance with the A-F six cups to divide the difference of 10, we count as B cup, 10 count below A cup. Based on this as a basis to body shape, breast shape, distribution of fat fat case, height and weight (this is mainly for online shopping friends) to adjust the size of the cup. But the adjustment is in accordance with the level of 2 cm liter, so the final are made of F H Cup, each system will have different standards, wearing different guidance, the same size underwear through different services will have different Feel and effect, which will affect the size of the visual judgment Third, a lot of surface materials of materials, texture different structures, toughness, tensile strength, resilience are not the same style design is not the same. Blended Yarn,Cotton Acrylic Blend Yarn,Comfy Cotton Blend Yarn,Cotton Blend Yarn Suzhou Zhiqin Textile CO.LTD , https://www.zhiqintextile.com
First, because there is no clear industry standard underwear industry and the strict requirements of each size standard.
The earliest is based on the introduction of foreign lingerie size to be set, with the development of the industry, brand diversification, product diversification, plastic function underwear, lingerie, underwear, and so the standard sub-standard fashion and no specific Standard, each brand will have its own set of standards on the basis of the original, of course, this is also closely related with the designer, so in this case to achieve the same size of all underwear brand is very difficult, at present Industry situation is even more impossible.
Second, this is related to each brand's product system and service system.
Sexy type and modified type are certainly different The former care more exposed dew, the less fabric, the less sense of restraint; and to achieve a modified shape can not be exposed too much, the scattered fat need to bind the abdomen , So the size of the elastic is not a complete system.
In addition many brand salesperson to see a very thin sister directly recommended A cup, busty give B cup, there was a very slim sister body is good, no meat anywhere breasts are very full, wear 70E, 70F, But always do not believe that there is chest. Now gradually do some of the C and D Cup, but some manufacturers designers and employers simply do not believe there will be wearing 70E, F people encountered such a body usually 75B, C replaced, which is why the plump The sister's breasts will droop and the reason for the emergence of milk. 
This requires designers to be very familiar with the material properties, and products to be presented in a very clear function to determine the size of the zoom, which designers and platesetter requirements are higher.
Finally, the standards of each brand manufacturers are slightly different, so the size of the market is difficult to unify. Even the formal big brands, the design department is also a designer of iron run camp, every change of designer, will change the size standard. So you can only go to the store to try on their own experience, or with a brand soul and the established standard of the brand go.
While looking forward to industry standards and norms, we also have to be a smart consumer, armed with knowledge of underwear, choosing the right one for yourself rather than following the crowd and becoming a true woman who really loves her.