Okay. This is SO trivial, but it has always puzzled me.
Misses dress sizes are even numbered-- 6, 8, 10, 12, etc.
Juniors are odd numbered-- 5, 7, 9, 11, etc.
If someone goes from a size 12 to a size 6, has she gone down three sizes (12 to 10 to 8 to 6) or six sizes (12 minus 6)?
I would say the former, because the Junior sizing is in another system, so you wouldn’t count those sizes.
What say y’all?
Three sizes.
If you went from a Large to a Small, how many sizes would you have dropped? Two. Only the steps inside a system count. It doesn’t matter if a different system has more intervals.
I’m a guy, so I only know slightly more than nothing about this (although I just now learned where all those odd sizes went, so now I know even more), but I’ve heard enough talk about dress sizing that the answer to your question would be “three” sizes, as I’ve always heard it used. I’ve never heard someone say they went down two sizes when they’ve gone from a 12 to a 10.
Yep, it’s three sizes. If you say “I like this size 8 dress, but I need it a size bigger”, you get a size 10; if you ask for it two sizes bigger, you get a size 12. Same applies to losing sizes.
People aren’t just small medium or large. I don’t understand why women’s clothes aren’t differentiated by measurements, like men’s are. I may have a 30 inch inseam, but I could have a 28 inch waist, or a 52 inch waist. Do women’s clothes not make such distinctions?
A size 12 is a size 12 no matter how tall or fat (or short or skinny) you are? It seems like women would have need even more measurements, since they vary more in the chest and hips department, and prefer more form fitting clothes.
Women have multitude sizings for cloths.
Jeans are usually sized in inches just like men’s jeans. Dresses, blouses, suits and other less casual wear can be in any one of a dozen size categories. A size in one will have different proportions from the same size in others. (Of course, sizes also differ from manufacturer to manufacturer, which can drive women insane, but within a manufacturer’s line the convention applies.)
Less expensive clothing does come in S,M,L,XL just as most men’s clothing does. I don’t know where you shop, but it’s standard for some things everywhere I go, include upscale department stores, for example, shirts other than dress shirts, as well as coats and even underwear.
Clothing in standardized sized is cut to fit the average person. Cheaper clothing will have fewer variations, so that it is easier to keep in stock. This applies for men’s and women’s clothing.
One could also get “fitted” clothing, that is either custom cut, or selected from a large variety of standard cuts, to match one’s exact measurements.
A size 12 will have a particular set of measurements in a particular line , no matter how tall or short you are. So a regular size 12 will probably be too long for a short woman and too short for a tall woman. That’s why there are petites ( or short) and long lengths. But there are only three lengths for pants ( not every inch or two like men’s) , and most of us have to either wear them a little short or a little long or have them hemmed. I wish I had ever seen womens’ jeans sold by inseam
But anyway about sizes from 12 to 6 is three sizes- which is really easy to see if you are familiar with the 7/8, 9/10, 11/12 range of sizes sometimes used for non-formfitting clothes because there are only minor differences between a size 7 and a size 8, which don’t matter in many styles.
Thank you, everyone. 
This, I assume, is why all two-piece swimsuits now seem to be sold as components, rather than in sets.
Well, no. “Size 12” has nothing to do with the woman’s height, it’s based on her chest/waist/hip measurements. However, what chest/waist/hip measurements correspond to “size 12” varies depending on the brand or even the style/cut. If I have a size 12 pair of jeans that fits me perfectly, I cannot assume that size 12 jeans from another brand will fit me equally well. When it comes to jeans a lot of women figure out which brand tends to fit their body type the best and remain loyal to that.
Jeans and other pants are sometimes, but not always, available in short/average/long leg lengths. As doreen mentioned, there are Petite sizes, which are cut for shorter (not necessarily thinner) women. There are also Tall sizes, although they’re hard to find in stores. Most department stores will have a Petites section, but the taller women I’ve known mostly bought Tall sizes through catalogs or online.
I’m a woman and I didn’t know where the ‘odd’ sizes went. The only items of clothing I’ve ever been able to buy in size 11 or 13 are jeans.
I think, in answer to the original question, three sizes.
I wish. No, they’re not, they use the same parallel number systems that other clothes do. They are also, like many other clothes, differentiated by modifiers like Petite (meaning shorter in the leg) Long (longer in the leg) or Regular (um, “regular” in the leg, I guess.)
Juniors are generally cut with less of a difference between the waist and hip, with a little less room in the thigh - generally, less curvy than Women’s sizes of the same style garment. So fairly straight shaped women can often wear Juniors, while those of us trending to curves often grew out of the Junior’s department even if we didn’t reach the highest number, just because Junior waistbands wouldn’t touch our bodies if the hips fit.
Well that depends on the brand. I just looked at a bunch of my jeans and about half are sized in inches (26/27/28/etc.) and half are of the 2/4/6 style of numbering.
(The answer to the OP is three, btw.)
Seriously. I hate shopping because I’m attracted to all the pretty Junior’s clothes, only I have what the older generation would call “birthing hips.”