Bra-making Sew Along: Vertical Seam Variation

(Hack Your Bra Part 2!)

I love a diagonally-seamed cup because it is especially pretty in lace, with an unbroken line of scallops across the top. But it’s been fun to play around with seam directions for different style and shape options.

vertically-seamed cups

In today’s tutorial, I’ll share two pattern variations you can make to your cup: 1. adding an additional seam to your lower cup for a 3-piece pattern and 2. changing the entire cup to a vertically-seamed one. I’m using the 2nd variation for my own bra which you will see in action next week!

A tip for these alterations: The main seams in a cup should cross over your bust point. In some patterns, there is a notch at that point–usually right at the apex–if not, find it on your bra and mark it on your pattern so you know where it is. After your alterations, walk your pieces and double check that the lengths of the actual seam lines match.

Adding a Seam to the Lower Cup

ONE: For a second seam in the lower cup, mark a line going from your bust point down to the bottom seam line.

lower cup seam #1

It doesn’t matter where the line ends at the bottom so feel free to experiment! In this example, I’m dividing the lower cup into two relatively equal pieces, which will result in a seam that runs perpendicular to the main seam.

TWO: Cut the pattern piece along the lines and trace your two new pieces. Draw in a smooth, even curve connecting the top and bottom seamlines. The curve should be fairly subtle.

lower cup seam #2

THREE: That’s it–your new pieces! Don’t forget to walk the seamlines and add 1/4″ allowances to the new seam.

lower cup seam #3

Vertical Seam Alteration

For this alteration, first mark where you want your seam to start and end. A vertical seam doesn’t have to be straight up and down–you could slant inwards or outwards. I found my starting points by marking these positions on a previous bra. It just so happens that my pattern–Pin-up Girls Classic–has a notch right at the center bottom, which is usually where a straight vertical seam starts.

ONE: Mark the bust point of your pattern.

vertical seam alteration #1

TWO: On both pieces, mark in lines on the top and bottom cups, going from the desired starting point of your new seam to the bust point. I rotated the bottom cup in this example so I could draw a straight line down the two.

vertical seam variation #2

THREE: Split these pieces apart on the lines. You should now have four pieces total.

vertical seam variation #3

FOUR: Line up the top and bottom pieces along the sides until the seamline along the sides of the cup form smooth curves.

vertical seam variation #4

The cross-cup seamlines will match each other for a short distance, but will not come together at the bust point. Trace off the these new inner and outer pieces.

FIVE: Depending on your pattern style and where the apex is, one side may have smaller “dart” than the other. In this case, the outer cup has the smaller dart, so draw your new seam line on this side first. Draw in a smooth curve connecting the two upper and lower pieces close to the bust point.

vertical seam variation #5

On the inner cup, draw another curve of equal length. Because the “dart” on this side is so wide, the curve will not go around the apex. (You need to take some out from that “dart”, if that makes sense!) You can use a measuring tape to find the right curve length.

ETA: The flatter these curves, the less length (and volume) the cup will have. In your fitting, experiment with them to find the shape you like. If you’d like to pull things in more, you can experiment with making the inner curve slightly flatter than the outer curve–a good tool to use in shaping!

SIX: Smooth out all the new seam lines, mark your bust point notch, and add seam allowances.

vertical seam variation #6

In the above illustration I’m also smoothing off that strap extension from my pattern, because I’m not going to use a fabric strap.

There ya go–a totally new cup!

I hope these are clear, so let me know if you have any questions!

Have a beautiful weekend, all. And get ready to start the engines–on Monday we’ll finally get to sewing and I’ll start with some cutting and layout tips. See you then!


  1. Pleated skirt says:

    thanks so much! the vertical seam is my fave bra and I am so excited to make this one. Drafting your pattern now, I am 32a, do you think I should reduce the curve on vertical seam in the area of bottom cup?
    Thanks again, very informative posts!

    • Amy says:

      Hi! It really depends on your shape/the shape you want! It will be the curviest around the bust point/apex. You can mess around with it till you find what you like. (I’m around a 32B and this is exactly what my pattern looks like.)

  2. Michelle L says:

    Looking forward to sewing! I plan to make a couple of basic beige ones first, I want to master those tiny 6mm seams before I move onto fancy ones, even though I love nice lingerie my wardrobe needs some plain smooth ones. Happy sewing everyone.

  3. Carolyn says:

    Thank you Amy! I shall have to give this a go sometime… Actually even before you did your previous hack your bra post, I had already started playing around with my KwikSew pattern, aiming to draft a balconette or demi-cup… I’m hooked! pun intended 😉
    Thank you for the un-ending inspiration!

  4. Katherine says:

    Great post! You really are getting beyond the basics and making this fun!

    Just thought I would mention a detail from one of my drafting books…in your steps to make a 3 piece cup, diagram 2, my book suggests making the curve in the bottom cups curve out from the line by 4 mm. Of course this can be changed in the fitting…just a staring point if anyone needs one.

    Happy drafting, Katherine

  5. Novita says:

    I’ve been wanting to do this variation on my Pin-up Girls pattern but always have doubt on how to really do it. Time to make a muslin now! Thank you so much Amy!

  6. scooter says:

    Hey, Katherine, this may be a dumb question, but are there fitting reasons why you might want to make either of these alterations (as opposed to aesthetic preferences)? I have made the pin-up girls pattern a couple times and always thought the shape wasn’t quite right for me, but I’m not sure how these changes would alter that…or is this one of those you-just-have-to-test-it things? 🙂

    • Amy says:

      Scooter, just like with princess seams, the more seams you have in a bra the more opportunities you have to refine the shaping and fit. A bra with 3 pieces including a vertical side piece that goes from the bottom of the cup to the strap (sometimes called a “power bar”) is really common in very supportive RTW bras. You could always try splitting that bottom cup and see how it changes things! I wrote about the cup shape of the Pin-up bra in this post after making it as a foam-cup bra. You can see the shape it wants to take in very stiff fabrics and vertical seams offer some different shaping options.

  7. melissa says:

    Hello, I just wanted to finally comment and say a massive THANK YOU to you for this Sew Along! I’ve been paying along at home and conferring with Norma on Twitter but hadn’t formally said hello yet. I’ve made 4 or 5 bras over the years but have never been 100% happy with the fit, so this has given me the impetus to give it another go, and I *think* I’ve finally cracked it (I say “think” because my muslin looked good, but I’ve come down with shingles on my toso over the past few days and now can’t try on my finished bra!!).

    • Amy says:

      Hi Melissa, thanks for sayin hello! So glad you came along and cracked your fit! Sorry to hear about the ickies but I’d love to see/hear what came out of it.

  8. Aistė says:

    Thanks for the post! I have one question though. What about the grainlines of the fabric once one makes horizontal cup seam into vertical? I have vowen fabric in mind of course.

    • Amy says:

      Good question! Most of the time in this kind of cup, the greatest stretch runs parallel to the neckline (the top line).

  9. Heather Lou says:

    So I finally sewed up a tester with the Elan and boy oh boy… it’s pretty grantastic on me. It’s huge. I was gonna take mucho off the top pattern piece and cut the wires down but after reading all your sewalong posts (several times, actually, cough) I may go this vertical route. Especially since Norma suggests it if your ladies like to travel east and west, as mine do. Wish me luck going balconette. Expect photos and frenzy this weekend if I get muddled…..

    • Amy says:

      Girl, you’re a trooper! Sorry to hear about it being too big… I sent you an email. But don’t get discouraged, it’s just a different style bra. Demis often hide what doesn’t fit on top, too–because there’s no top to fit! But feel free to shoot me pictures if you need another eye ;).

  10. Ana says:

    Hola, donde encuentro el molde ? Puedo imprimirlo ,que talle es?me gusta la explicación,te felicitó desde ya muchas gracias

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