Saturday, 4 June 2016

Dress Cup Size is NOT Bra Cup Size!

I don't have a large bust but I do have a very small waist, which makes for a relatively high bust:waist ratio. Many people in the bra-fitting community struggle just as much with finding shirts and dresses that fit the bust as we do with finding bras outside of the matrix  (32A - 38E). I myself struggle with finding dresses that fit the top half of my body (US RTW size 2 - 4) and the bottom half of my body (US RTW size 00 or 0). One way to solve this problem is to buy RTW bust-friendly clothing. Another way we can solve this problem is by making our own clothing!

Before you get out your fabric scissors, we should go over one really important concept: Dress cup size is NOT bra cup size! In fact, when you properly measure your bra cup size and your dress cup size, you will most likely find that your dress cup size is smaller than your bra cup size! For example, 30D and 28DD are my most often worn bra cup sizes, but I need a 'C' in dress cup sizes. You might find that you normally wear 32F in bra cup sizes and a 'D' in dress cup sizes. 

Contrary to some people's ideas (I have had a commenter on my blog and on another forum guess that dress cup size is "the bra size you'd get with the +4 method"), DO NOT USE THE UNDERBUST +4" METHOD. The underbust +4" method is just as inaccurate for determining bra cup sizes as it is for determining dress cup sizes. When determining your dress cup size, use the overbust method. Getting your dress cup size is as easy as 1, 2, 3...

Step 1: Before measuring, wear the bra that you would most likely wear with the garment that you want to make. 

Step 2. Take your overbust measurement.

Step 3: Take your full bust measurement, then subtract your overbust measurement from your full bust measurement. 

Example:" if your overbust measurement is 31" and your full bust measurement is 34", 34 - 31 = 3. Therefore, your dress cup size is 'C'. Here is the chart for dress cup size progression:


  1. Do you have suggestions for how to measure dress cups size for tall or high-set breasts? The tops of my breasts are several inches higher than my armpits, so I'm not able to do a proper "overbust" measurement with the tape measure parallel to the ground.

    1. You should still do the overbust measurement the regular way. The reason is because shirts and dresses are constructed to fit at the broadest part of your ribcage, and then again at the apex of your bust. It's okay if doesn't take into account underbust because it's not a bra and it doesn't absolutely need to fit snugly at the underbust.

      I myself have tall roots and my roots begin somewhat above armpit level. I still measure my overbust the regular way. Think about how shirts are made. They are not like bras. Bras have a band that goes under the bust, two cups, and adjustable straps. They don't go around the overbust. Shirts and dresses cover your entire torso, and so if your roots are tall like mine, you still have to factor that into your overbust measurement. If I didn't have tall roots my overbust measurement would probably have been less than 30", but my shirts and dresses have to cover my torso up to my collarbones. If I made a button-down shirt with the overbust measurement being 29" then I wouldn't be able to button it together!

    2. I'm having trouble understanding what you mean by "the regular way." Do you mean keeping the tape parallel from my underarms (which is basically just measuring the apex of my bust due to how high-set and FoB my breasts are) or pulling the tape up at an angle from my underarms so it goes over the top of my breasts?

    3. It should be parallel to the ground. Even if there is a small difference between your overbust and your full bust measurements, that's okay. That just means you'll need a dress or shirt sewing pattern size with a relatively larger overbust measurement (sometimes referred to by sewing pattern companies as "high bust measurement")

    4. Hmm, my overbust and full bust measurements are just under 1" difference, which would put me in an A cup. Isn't that smaller than the standard cup size in patterns that don't have specific cup sizes? Those already are too tight in the front at bust height while too loose in back and circus clown levels of too big in the shoulders if I size by full bust measurement. Would sizing by overbust and cup size make these issues worse, or am I misunderstanding how this works?

      Also, thank you for taking the time to answer my questions. :)

    5. Here's the thing: while you could try a smaller pattern size with a larger dress cup size, it will still be too tight at the armpit level, even if it feels right at the apex of your bust. For example, if you were to make the Muse Philippa dress in pattern size 30, dress cup size D (Muse uses New Zealand pattern sizing), it might fit well at the apex of your bust but it might be too tight at the armpit level.

      It is true that sewing patterns with dress cup sizes don't take into account people with very tall roots or people with a very high-set bust. I guess what you're looking for is a high bust adjustment. Here is a tutorial on how to do it:

      My guess is that once you do the high bust adjustment you will not need an 'A' in dress cup sizes. As your breast roots start so far above your armpits, there is no good way to measure dress cup size for you so I guess just start with a 'B' in dress cup sizes, make a bodice muslin (no sleeves, no skirt) of a dress, then make the same thing with a 'C' in dress cup sizes if the 'B' cup didn't work. Repeat until you find a dress cup size that works for you.

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