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Robin Bra Sewalong

5 Lessons taught by Haley

567 Seamwork members have watched this class.

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Lesson 2: Size & Fitting

Drop what you think you know about your bra and cup size and dive into the size chart. In this lesson, Haley will walk you through selecting a size and adding or reducing fullness, if you need to. Remember, making a muslin is key to getting the best fit!

If you need any help selecting your size or making adjustments, be sure to share in the Community.

Click the timestamps to skip to these sections:

  • How to use the size chart to select a size (00:22)

  • Prepare your pattern pieces (02:26)

  • Add fullness (05:12)

  • Reduce fullness (05:26)


Let’s talk about selecting a size and fitting. This might feel like kind of an intimidating step, but I’m going to invite you to drop what you think you know about your bra size, your cup size, all of that business, and just dive into that size chart. Let’s get started, and I will show you how.

So when you’re choosing a size for your Robin bra, of course, you’re going to want to consult your size chart. We have a lot of really helpful notes in this size chart. And what we’re suggesting is that you compare your full bust measurement and your under bust measurement to the body measurement chart. And then if those two measurements are falling into two different sizes, go with the smaller size.

This is because the negative ease in this garment, which you can see illustrated in the finished garment measurements below, is doing a lot of the heavy lifting here. So try not to get too caught up in what you think you know about your cup size and really lean into these body measurement charts and then go with the smaller size indicated.

Just like all of our patterns, we have the size 12 - 26 range, and then we also have the sizes 00 - 16 range, and the 12 - 26 is just drafted for a little bit curvier body style and a little bit fuller chest.

Okay, so in this particular pattern, I am a super lucky ducky, and I fall exactly into the size 14 in the 12 - 26 range. So my bust is 42 inches and my under bust is 36 inches. So I won’t need to do any kind of adjustments or anything. Even if I was like a 43 here or a 44, I’ve made this bra, I’ve seen this bra fit on a bunch of different body shapes, and I still would go with the 14 and probably wouldn’t fuss too much with fitting.

But if you want to create a little bit less fullness in the bust or a little bit more fullness, I’m going to show you how to do that.

So here I have my front pattern piece, my side front piece, and my center front piece. And if I was wanting to decrease or increase the fullness, these are the two pieces that I’m going to want to grab. To increase or to decrease the volume is going to look the same kind of regardless of whether you want to increase or decrease, you’re going to start by drawing a line perpendicular to the grainline, right above that lower notch.

I’m going to start on the side bra piece, and then I’m going to do the same thing over here on my center bra piece, perpendicular to the grainline and above that lower notch. While I’m here with my ruler, I’m also going to make a little mark for my seam allowance right near this line, so I can be conscious not to mess with my seam allowance unless I absolutely need to. Okay, and the seam allowance for this pattern is 3/8 of an inch. Okay, everything is all marked.

So next, what I want to do is to slash along these lines so that I can kind of open and close, think of like Pac-Man. So I’m starting at the bust, moving towards the side seam of the bra, and I’m going to stop right at that seam allowance mark that I made, and then I’ll go in on the other side of the seam allowance and just make a little notch. So what this allows me to do is create that kind of like Pac-Man mouth I was
talking about.

To create more volume, if you have a fuller bust, you need more height to your cup and that’s so that it covers all of the breast and that you’re not spilling over the top. So extra height is going to do a lot of good for you. So you can open up that Pac-Man mouth to create more height there.

The opposite is true if you need less volume. If you need less volume, you need less height to your cup so you can kind of close that mouth to create less coverage up top and all of that extra coverage in length if you don’t have the breast tissue to fill it out, is going to look really baggy right here and it’s just not going to sit right underneath your clothes.

In the next lesson, I’m going to talk about finding all of your supplies and the fabric.

Robin Bra Sewalong

Here’s what you’ll need for this project:

  • Robin bra pattern

  • Light to medium weight knits with four-way stretch with 50% stretch and good recovery

  • All-purpose polyester sewing thread

  • Ballpoint sewing machine needle

  • Four 1/2” (13 mm) rings and two sliders

  • 1 1/2 yards (1.4 meters) 1/2” (13 mm) of wide bra strapping

  • 1 1/2 yards (1.4 meters) of 3/8” (10 mm) picot elastic

  • 1 yard (.9 meters) of 3/4” picot elastic (20 mm) (sizes 00 - 16) or 1” (2.5 cm) picot elastic (sizes 12 - 26)

  • One hook and eye bra closure. Sizes 00-16: 3 hook closure finishing at 2 1/4” (5.7 cm). Sizes 12-26: 4 hook closure finishing at 3” (10.2 cm).


Work alongside other sewists by participating in the Seamwork community. Ask and answer questions, share your progress, get inspired by real-life sewists, and post your finished projects.

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