How to determine what size your bra was drafted for

How would you like to know what size your bra was actually drafted for?

Since there are so many different ways people measure for fitting bras, I thought I’d try to shed some light on why some people measure some ways and why some people measure other ways.

The first thing to cover is how people measure. I have encountered 4 different measuring techniques, but the one thing that is common among all of them is that you subtract your band number from your full bust measurement to determine your cup size. For each inch difference, there is a cup size.

The differences come into play based on how to come up with the band size. The most common measuring technique is to take your underbust measurement and add 4″ or 5″. Specialty shops generally take your underbust measurement and add 2″ or 3″. International measuring either take the underbust measurement as your band size or your chest (above the breast) measurement as your band size.

So, which one is correct? The short, but frustrating answer is, “All of them.” Each one of them were developed based on how a pattern was drafted, but how do you know what measurements they were drafted for?

The next short, but frustrating answer for that is, “you don’t know.” I am on a quest to find out what sizes these bras were drafted for.

I started with a paper with a line on the far left. I also did a lower horizontal line, but that was unnecessary (skip that if you are doing this yourself). I pinned the center of each bra and lined up the center front to the left line.

I first marked the position of the wire with it just sitting. I then straightened the band, which moved the wire and marked the same point on the bra with the wire sprung. That was done for a later post, but thought I’d explain what I did.

With the side of the band straightened out, I marked where the side seam was on both the top and bottom of the bra, then marked where the back ends before the hook & eye.

Each one of these is a different manufacturer, let’s determine what size these were actually drafted for. I did a video as well (link is at the bottom) but it might be a little technical and boring, except for the parts where the cat tried to get some love while I was filming.

I repeated this for 4 different bras. Notice that the angles of the side seam are very different, meaning that the body proportions these were drafted for, were very different as well.

I marked a horizontal line from the center front to the top and bottom of the side seam and indicated the measurements.

I then drew in the back lines from the side seam to the back and measured those as well.

Once all those measurements were recorded, I then tested the back for stretch. Now, the one thing I had taught in my previous books is to take into account the stretch of the back fabric, but in actuality, you need to know the stretch of the elastic, which is generally snugger than the fabric. In fact, you can really use any stretch fabric you want for the back, IF you have the right elastics to stabilize the fabric.

Ok, so to test the stretch, I tested the elastic itself. I marked in pins at 0 and 5″. I then lined it up to a vertical and horizontal line and stretched the elastic to a comfortable stretch. This stretch was not the full amount the elastic stretches it, its the amount it stretches before you hit resistance. The point beyond resistance can be very uncomfortable.

I then referred to my stretch ratio chart and reverse engineered the back lengths. I took the amount of the back (and really only the underbust measurement matters) and divided it by the stretch ratio to determine what the measurement it should fit on a person.

Ok, now I’m jumping around a bit. Lets first determine the difference from chest to underbust. Subtract the underbust from the chest amount for the front and multiply by 4. That is the difference for the entire bra between the chest and underbust measurements.

To determine the actual underbust measurement this was drafted for, add the front band, the new underbust measurement on the back plus 1″ for the hook & eye. Then multiply by 2. Voila. That is the underbust measurement this was drafted for.

Then add the chest difference to determine what chest measurement this was drafted for. Voila. Now you know.

One thing to note is that bras are designed for generally the smaller measurements in a range, so a comfortable fit would be for those two measurements plus up to 1″, maybe 1 1/2″ max.

The next question I approach is which measuring guidelines match each of these bras:

Black Bra: 38C by Maddie & Coco (cheap bra from Bealls)
Measurements drafted for: Underbust 30″, Chest 35 1/2″
Measuring technique: Chest +2/3 or Underbust +8
5 1/2″ Difference from Chest to Under Bust

White Bra: 38B Body Frosting (cheap imported brand)
Measurements drafted for: Underbust 31″, Chest 33 1/4″
Measuring technique: Chest +4/5 or Underbust +7
2″ Difference from Chest to Under Bust (approximation)

Nude Bra: 40C Wacoal
Measurements drafted for: Underbust 32 3/8″, Chest 35 3/4″
Measuring technique: Chest +4/5 or Under bust +7/8
3 1/2″ Difference from Chest to Under Bust (approximation)

Brown Bra: 42C by Pink (Victoria Secret),
Measurements drafted for: Under bust 36 5/8″, Chest 41 3/8″
Measuring technique: Chest measurement
5″ Difference from Chest to Under Bust (approximation)

Ok, I was not expecting those measurements for those sizes. Now I’m curious what the manufacturers recommends.

Just checked Wacoal. They recommend under +3/4, but no mention of the chest. As far as I can tell, this bra was possible drafted based on the fabric stretch and not the elastic stretch. The fabric stretched far more than the elastic did. Wacoal always fit me best, but the bands were often a little tight for me based on their recommendations.

I also checked Victoria Secret and at least their measurements match their recommendations. The other two brands are cheap and likely made in some factory with little to no reference of sizing.

I can see why so many people wear the wrong size bras. It isn’t really an issue with the measuring, it’s an issue with the drafting. Every part of the bra needs to be accounted for, in every aspect of the draft. (A wire discussion will be a later post.)

The elastics play an integral part to the way a bra fits and if the bra is only being drafted based on the fabric and the elastic isn’t incorporated into it, the bras can fit drastically different based on which notions are used.

Why don’t you try this yourself and share with me what you discover about your favorite brand. How does their measuring size up to the actual bras you have?

Here is the full video:



This is all part of the research I did for the third edition of my bra drafting book. Now, I know that some of you are wondering why I would write a third edition in 7 years. Not sure if you knew this but the big textbook publishers do a new edition every 2 years, so I’m not far off.

BUT, I do not plan to write another edition of this book, EVER! When I wrote my first book, I researched all the available information out there and tested and tested. I developed my own drafting techniques and they worked. I still say that they worked, even though I am writing the 3rd edition.

What changed is me. My body changed after having a child so I began to look at drafting a whole lot differently. The second edition also included instructions on how to draft in CAD. The second edition I am also proud of. I have found a few typos and wording that could have used a little more editing, but the second edition showed different ways to do the same thing.

Over the past 3 years I have gotten involved with a few bra making groups on Facebook. It has opened my eyes to even more issues that ALL bra drafting neglected to address.

I decided last year that I was going to do more scientific and mathematical research to thoroughly understand the underlying issues and how to fix them by drafting a truly custom fit. That is what I have been working on.

I created a calculation to determine the horizontal measurement for a cup draft based on the wire size, under bust, full bust and chest measurements. I then was able to create a calculation to determine the vertical measurement of the cup incorporating one additional measurement, the chest height. With these new calculations, I have been able to get to a more accurate draft on the first try.

Those are just some of the reasons for the third edition. I’ll share some more in my next post.

The complexity of altering a bra sloper

I created this draft of a stylized bra design from my completed draft. It a bit complex if you have never done pattern drafting before, but know that there is a light at the end of the tunnel. When manipulating a pattern you need to remember this important rule – what you take away from one piece in volume you need to make it up on another pattern piece.

This isn’t going to result in a perfect fit after each pattern alteration, so it is important to test the fit prior to moving on to good fabric. I wish you all luck in this journey. The more designs you experiment with, they more knowledgeable you will become.

Here is my challenge. Draw a bra design and submit it to me for a drafting tutorial. I am open to as many as possibly. Let me know what your starting bra is and we can work from there. Not all designs must be created from your initial draft, so if you are daring, maybe submit the new design and scan and send in your starting pattern as well. The more challenges I receive, the more education I can pass on. You can email them to me at jennifer at porcelynne. For me to post, I will need to know which pattern you are starting from (if its another design out there) with the link to the product so I can share it will everyone.

Here are your videos for today.

Splitting the Lower cup from the Bra Draft

I have done a few new videos and this is the latest. This takes the drafted bra sloper we created and splits the lower cup for fit. This will help you get a better idea of the fit. Splitting the lower cup is really just for practice as you may not want a cup with a straight seam across the cup with the split lower cup. This is a good first step to understanding the manipulations involved with changing a bra draft.

Altering your Bra Pattern for a Different Size Wire

I worked on this little video after I had a few questions regarding using a different wire size with my bra pattern. This one is specifically for changing the wire size, but not the wire type. I will work on a different video for changing the wire type.

To Error is Human

I never claim to be perfect, so please never quote me as so. I actually skipped a step when drafting the back of the band, but this video shows you how to compensate for missing the step.

Drafting has Commenced

To put a smile on everyone’s face, I have finally filmed my first set of drafting videos for creating your own bra sloper. I’ll keep this short, as I know everyone wants to begin drafting yesterday, so here it goes. Happy watching!

I goofed again

For those of you getting ready to follow my draft, I just realized I goofed on a chart in my new book! Agg! I did this last time too. I swear all this math will get the best of me yet. I posted a bra size chart in one of my videos and it was off by 2 sizes on everything! I triple checked that stupid wire chart about 10 times and changed it that many times as well before the update of the book. I know it was correct, so a little gremlin must be sabotaging me. I’m so sorry if someone bought the wrong wire based on my video. I will make it up to you I promise.

Final set of measurements for the custom draft

I had intentions of getting this video done on Monday, but my shop was a disaster and I had to work on cleaning my desk off. I finally completed clearing my desk off yesterday, so here is the promised video. Please disregard my difficulty in holding my wires for measurements. Please measure in front of a mirror and not in front of a camera.

These directions are what you will need for your custom drafted sloper. I’ll begin recording the drafting tomorrow, but they might not be available until next week.

Another reason I have been slow to post is that I’ve been working on grading a new pattern for my website and in the process, I recorded the steps with the software on how I did it. Those won’t be available until after I complete the drafting directions, so know I have some goodies coming soon.

I make a mistake in the video when I’m talking about the wire size I’m using. See if you can find it.

Preliminary steps for drafting your own bra

I made a couple “raw” videos on measuring. These are just the first steps. There will an additional measuring video once we begin our draft. I will be filming the draft in many steps and will so shorter 5-8 minute videos of each step so its easier to keep up. But for now, this first video is a basic how to measure for your “standard” bra size. I put standard into quotes, because no body actually really fits a standard size.

The standard size measure is to find your starting point. In this video I measured 37 under and 41 over and chose the 38 band to work with. One thing I didn’t mention is that if I were to try on a ready to wear bra, I might also try the 40 band, but step down to the I cup.

Bras are complicated and there is really no one right way to do it. So take a deep breath and forget the numbers and letters you are coming up with and just go with the flow.

This second video is to help you determine which wires to try out when ordering. The larger the cup, the more challenges you might have, so you might need a wider range of wires to test. If you are smaller, meaning you are less than a G cup, you can probably try the suggested wire and then go up and down a size to test too. Bra making in its initial steps is going to be expensive, but once you have the hang of it, you will be creating beautiful bras and at a fraction of the price you’d be buying them in the fancy stores.

UPDATE: Before watching the following video- print this following chart out. I published the wrong size chart in both the video and the first printing of the book. I just updated it, so any new book purchases after 11-1-2016 should have the correct chart.

Remember that most places you order wires from do have a return policy, so extra wires can always be returned, but as a small business I need to express – you will be responsible for shipping costs for returns whether the wires you order fit you or not. And I know this goes for all the other bra wire suppliers out there too. Wires do not come in a one size fits all package. There can be hundreds to choose from, including demi, short, long, etc. The draft we will be working on is a full coverage “block.”

This means that this draft can be manipulated into other shapes and sizes, so your initial draft might not be the best shape for you. We will get to that after our draft. See you soon for our draft.

Adjusting strap placement

In this sample we are moving the strap placement.

Step 1: Draw in your seam allowance at 1/4″

Step 2: Take your two patterns pieces and overlap the seam line and tape down.

Step 3: Use the french ruler and reshape the strap position

Step 4: Cut off change and tape down to the new position.

Step 5: Separate the two pattern pieces.