Determining Your Cup Size

Determining Your Cup Size

In my latest test for the Sandrine Tank, it was brought to my attention that I had failed to explain how to determine your cup size for my patterns! I can't believe I overlooked adding such a simple explanation to my patterns before, so I am here to right that wrong!

Determining your cup size for my patterns may differ from determining your cup size for traditional bras as well as from another indie designers patterns. And your cup size may vary from pattern to pattern depending on:

  • What undergarments you plan to wear with your finished outfit
  • The amount of ease you prefer in your finished garment
  • If you are layering additional clothing below your finished garment

These are all things you might want to take into consideration when figuring out which cup size to start with.

I suppose I should mention here that all of my patterns come with both a B-Cup & DD-Cup draft unless there is LOADS of ease in the pattern and my testers have told me that additional cup sizes are unnecessary (as was the case with the Olive Jumpsuit where the majority of my testers with larger cup sizes said that there was plenty of ease for them!)

To determine your cup size, you will need only two measurements:

  1. Upper Bust
  2. Full Bust

Simple, right?

As I mentioned above, you will probably have different undergarments to wear for different styles, so it is best to take your measurements while wearing the undergarments you plan to wear with your finished outfit. Each bra we wear alters the shape, fullness, and location of our busts in conjunction to the patterns we are working with, so it's best to take these measurements each time you go to work on a new project!

For me, I have a smaller bust so I tend to wear soft bralettes or go sans-bra. Therefore, I am taking my measurements in a light bralette for the most accurate results.

First, align your measuring tape parallel to the floor and bring it across the fullest part of your chest. Generally, this will cross over the apex of your bust (right across the nipples). Make sure that you are not holding your tape measure too tightly, thus squishing your breasts.

I always like to make sure I can fit at least two fingers in between myself and my tape measure and I always take a nice deep breath as I like to make sure I can comfortable breathe in anything I plan on wearing.

The measuring tape got a little wonky in this photo, but rest assured, when I took my measurements I made sure everything was aligned properly. It's hard to do a self timed photo of yourself with everything perfectly in place!

Once you have your measurement, write it down someplace. For example, I would write down

FULL BUST: 37.5"

Next, you will want to take your Upper Bust measurement. To measure your Upper Bust, slide your measuring tape just below your armpit. Your measuring tape will NOT be parallel to the floor for this step. Instead, it will have a slight angle to it as you wrap your tape around your body, under your arm, and over the smallest portion of your upper chest as shown below.

Again, I like to take a nice deep breath here and allow enough room for at least two of my fingers to reside between the measuring tape and myself.

You will want to write down this new measurement right next to your Full bust measurement:

FULL BUST: 37.5"


The next step to determining your bust size is to subtract your Upper Bust measurement from your full bust measurement. This final number will determine your bust size for my patterns (again, this may vary from designer to designer, so always be certain to check!). I have put together a super simple table below so you always have a reference as to what your cup size might be!

Using myself as an example:

FULL BUST (37.5") - UPPER BUST (35.5")  = DIFFERENCE (2")

I would then look at the chart below and see that a 2" difference between my Upper and Full Bust puts me right at a B-cup!

1" (2.5 CM) A
2" (5 CM) B
3" (7.5 CM) C
4" (10 CM) D
5" (12.5 CM) DD
6" (15 CM) DDD
7" (18 CM) E
8" (20.5 CM) F
9" (25.5 CM) G
10" (23 CM) H
11" (28 CM) I


I hope this quick tutorial helped! Feel free to let me know if you have any questions in the comments below or by emailing me at :)

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