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icon free“I must, I must, improve my bust”

This is my first article on bra pattern drafting (drawing) and construction. But for this article you do not need to get out the sewing kit and fabric just yet, as we need to sort out one main problem: what size bra do you want?

Almost every day, bra companies and fashion magazines declare that 70% of women are wearing the wrong sized bra. I believe that this is a nonsensical statement, as we have no standard breast measurement and size labelling system that is recognised around the world, and many women are happy and comfortable to wear their “wrong” sized bras. In writing articles about bra pattern drafting and construction for a website that has followers from around the world, we must first overcome a worldwide problem:

“What is my bra size?” 

When a designer produces a new bra for the British market, the prototype is made to a “core size”. In Britain this would be a UK 34B (even though the average bra size in Britain is now about 36C/D). This prototype is then “graded” (enlarged or reduced) to produce the other sizes.

But a British 34B size bra can also be labelled as

  • 34A in the USA
  • 75B in Europe and Japan
  • 90B in Spain, France and Belgium
  • 2B in Italy and the Czech Republic
  • 12B in Australia and New Zealand.
  • B75 in Japan

And to make matters worse, the identification of cup size by letter is not consistent across the globe: 

  • UK: AA-A-B-C-D-DD-E-F-FF
  • UK specialist: G-GG-H-HH-J-K-L
  • American: AA-A-B-C-D-DD-DDD
  • European: AA-A-B-C-D-E-F

The EN 13402 industry standard - AA, A, B, C, D, E, F, G, H, I, J and K - will eventually help resolve the current confusion surrounding cup-size codes, but only in Europe.

As well as no standard bra size classification systems, the antiquated way in which women are measured for a bra is far from satisfactory, as it does not take into account the volume of the individual breasts and the variations in back size.

You know the drill: for UK sizing, measure in inches around the chest just under the breasts, then add 5” if the measurement is an odd number or add 4” if the measurement is an even number. This is your “Band size” - 30, 32, 34, 36 and so on.Determining your band and cup size Now measure around the bust at its fullest part and take the band measurement (+5 or +4) away from this measurement. The difference - 1”, 2”, 3”, 4” - indicates your cup size.


  •  29” + 5” = 34” band size
  • 34 back size and 35 full bust is a  +1” difference  = B cup

Think about this measurement method applied to two body shape extremes.

  • A woman who measures 29.5 inches around her ribcage and 35.5 inches around her overbust, but has a narrow back and full breasts.
  • A woman who measures 29.5 inches around her ribcage and 35.5 inches around her overbust, but she has a muscular, wide back and small breasts.

Using the traditional measuring method, both of these women would be offered the same size bra, but they have significantly different body shapes.

So for the bra pattern drafting and making articles I will use a simpler and more accurate bra cup size identification and measurement system. More on that later.






Parts of a typical Bra.

So that we are all “singing from the same hymn sheet” and you know what I am referring to when I am writing about bra pattern drafting/construction, here are the parts of a typical bra.

Parts of a Bra

By the way, in the industry a garment pattern that you are working on to change the style or size has no seam allowance and is called a “Block”. When you have made all the changes, you then add the right seam/hem allowances.



The big headache about bra pattern (block) grading.

When we want to change the size of a bra pattern/block we could draft a new block for the new size, but in the industry a single “core size” block is “graded” (adjusted) to produce the other sizes in the range.

Take, as an example, the British bra size system. There are 16 cup sizes, AA - A - B - C - D - DD - E - F - FF - G - GG - H - HH - J - K -L, and 6 band sizes from 30” - 40”. That makes 96 size options. Multiply that by 2 colourways (ie making white and black bras), and you and your company potentially have 192 different bras to make!

BUT what if you could use parts of one size bra in a different size bra? You can!  Welcome to the world of bra CROSS GRADING.

If you take the cups and the cradle/underwires of a 34B bra and shorten the wings by the right amount, you have a 32C bra! Likewise, if you lengthen the wings on the cups and the cradle/underwires of a 34B bra by the right amount you will have a 36A bra! The same goes for other Cup/cradle sizes: - the cups/cradle of a 38D bra are the same size cups/cradle as a 40C bra, and 36DD bra and a 34E bra, and so on and so on.

The tabel below shows cross grading using EN 13402 standard cup lettering.

Same cups and cradle





Same cups and cradle





Same cups and cradle






Same cups and cradle






Same cups and cradle







Same cups and cradle







Same cups and cradle







Same cups and cradle







Same cups and cradle







Same cups and cradle







This cross grading system is also used for bra underwires: the underwires that are used in a 34B bra can also be used in a 36A bra, and so on.


Size/band grading

The standard step increase in band size is 50mm (2"), which takes a 34B to a 36A, for example. (Some European brands use a 40mm underband increase instead, which can result in a much smaller and tighter fit in large band sizes.) The underband will increase by 50mm; a quarter of that increase must be placed in each half cradle and wing, as shown in the diagram below.

 Classic 50mm Bra Grading




Cup Grading

To get from 34B to 34C, for example:

  1. The underband length remains the same.
  2. The cradle must increase to provide the larger cup size, but the wing must get smaller to maintain the underband length.
  3. The cup section is graded one size larger.


Darted Bra 50mm Grading Rules.

So here are the three grading principles for bras.

  • Cup Grading: - to increase the cup volume, the cradle of the bra must also increase to accommodate the increase in cup size and the wing must be reduced to maintain the band size.
  • Band Grading: - to increase the size of the band, but maintain the cup/cradle size, (eg 34B to 36A, or 34B to 36B) combined with cup grading.
  • Cross Grading: - to use the cups and cradle of one size as the cups and cradle of another size bra (eg 34B cups and cradle used for a 36A bra).

Darted Bra Grading

When we draft (draw) the bra pattern, we will do some grading to make the cups and underband to your size. The manual method of grading bra patterns that we will be using is called “shift grading”.

It uses vertical and horizontal axis lines, which must be at right angles to each other on each pattern, or “star” lines radiating from a “Cardinal” point. You can do the pattern and grading on a computer if you have a good “Vector Line” drawing CAD (Computer Aided Design) program such as AutoCAD, Corel Draw or Adobe Illustrator. I personally use Corel Draw.

That’s enough of the world's sizing problems; we need to get on with the stuff that you need to know to make a bra.

So what is your size?

I mentioned that I would employ a different measurement and sizing method for these articles. So get out your tape measure and take all measurements in CENTIMETRES (sorry America and Britain, it's metric all the way from here). Write all the measurements down. If you're not making your own, and you don't have a particular client, family member or friend in mind, then use the measurements for a “Size 4 cup” and a “50cm back” (equivalent to a UK 34B core size). 

When taking all measurements, try to be as accurate as possible (to the millimetre).

The first two measurements you need to take are your “Over Breast” measurements, from the “breast root” at the side to the “breast root” at centre front. Your “breast root” is the line where your beast joins the chest wall and where the wires of a correctly fitting underwired bra should sit. When taking the measurements you should wear a good fitting underwired bra that lifts the breasts up into the fashionable full shape; the underwires in the bra should help you to identify your “breast roots”.

I know it’s a “Chicken or Egg” situation - to take measurements to get a well-fitting bra you first have to be wearing a well-fitting bra! But I am still working on a simple way to get the dimensions/volume of clients' breasts without going to a local hospital and using their MRI body scanner. 

Take the measurements horizontally over the fullest part of the breast from the “breast root” at the side to the “breast root” at centre front. Measure both breasts, then use the larger measurement. Do not worry if the two breast measurements are different, no-one is perfectly symmetrical.

Measuring over the breast Measure from wire to wire, if wearing a good fitting bra

Now refer to the table to find your cup size, and make a note of it:

Over breast measurement Cup size Over breast measurement Cup size
14.1cm to 14.7cm 1 45.1cm to 46.8cm 16
15.8cm to 16.4cm 2 41.3cm to 41.9cm 17
17.5cm to 18.1cm 3 43cm to 43.6cm 18
19.2cm to 19.8cm 4 44.7cm to 45.3cm 19
20.9cm to 21.5cm 5 46.4cm to 47cm 20
22.6cm to 23.2cm 6 48.1cm to 48.7cm 21
24.3cm to 24.9cm 7 49.8cm to 50.4cm 22
26.0cm to 26.6cm 8 51.5cm to 52.1cm 23
27.7cm to 28.3cm 9 53.2cm to 53.8cm 24
29.4cm to 30.0cm 10 54.9cm to 55.5cm 25
31.1cm to 32.8cm 11 56.6cm to 57.2cm 26
33.9cm to 35.6cm 12 58.3cm to 58.9cm 27
36.7cm to 38.4cm 13 60cm to 60.6cm 28
39.5cm to 41.2cm 14 61.7cm to 62.3cm 29
42.3cm to 44.0cm 15    

So if you measure 19.6cm over the fullest part of the breast from the “breast root” at the side to the “breast root” at centre front, then you will draft/grade/make a size 4 cup. If your over breast measurement is between·two cup sizes, go for the higher cup size.


Measuring for the band measurement

The Back/Band Measurement

Again, locate your breast root at the side of your breast, take the tape measure around your back horizontally to your breast root at the side of your breast on the other side. Make a note of your Back/Band measurement.

Now we're ready to begin drafting in the next article.


An extra note to all the mathematicians out there: have a think about how you would determine breast volume and the dimensions to put that breast volume in a fashionable shape...


Click here to go on to part 2 of the "How To Make A Bra" series

Jean Gormley
Great website, cant wait to read more!
I have been doing a little research about bras and i came up with a formula, to put "put breast volume into a fashionable shape" Will you be willing to help me test it.
I will try the method out.
Dawn Mason
lolLooking forward to the next part.As I am allergic to so much in bras I have to wear ugly white cotton sports bras which do nothing for my self confidence .
Shirley A. Stanley
Don't laugh before you think carefully about it. How about trying "water displacement" as a means to measure breast volume? I know it would be really awkward, but might it possibly be "doable"? It would certainly be less costly than the local hospital MRI machine. To do this, a container (bowl, whatever) containing a known volume of water would be placed on a firm, waterproof surface. The breast would be submerged, being careful to submerge all, and only, those parts of the breast intended to be covered by the bra cup. Of course, this breast mass would make a corresponding volume of water leave the bowl. Then, once all had settled, the breast is removed and the remaining volume of water in the receptacle measured .
That's exactly the method I've been considering; I think it's a great idea!
I was thinking along lines. thing is water displacement is easier calculated with putting the first bowl to a pot with scale outside it if you don't want to get low precision. or possibly have the first pot have a scale. By the way anyone has any idea how to create bra like structure by crocheting in crochet corset(well corset look a like , it doesn't have to actually shape body just be well fitted)? I intend to make wedding dress by crochet and advice would be valuable as my design calls for all to be continuous ( having least amount of individual pieces of crochet stitched together as possible). I think I could try to make it as one part with rest of dress but I won't have it flattening my girlfriend because she would hate it
Sharon Redmond
I took my cup measurement and it is 59 which is not listed on your chart. What do i do now?
Hi Sharon Redmond
I will put up an extended cup size table shortly, but in the meantime think about “Grading Steps”. The step between each cup size is 1.7cm and the grading steps for the line lengths are at the top of the table.
Will be as quick as I can with the table.
Corset Hugs

Amanda Boissoneault
Mark, when you talk you sound like Dave, a teacher who teaches bra drafting at DMU, Where you his pupil at one time? Very well written instructions. When I went to learn to draft plus size at DMU we took 34B which became very distorted in grading. It was odd we were informed not to grade above a certain size and then they weren't practicing what they preached. I had to develop my own formula to eliminate this distortion.(15 grades and no distortion) I really like the math for the dart bra. Never seen it before.
Hi Amanda,
So so sorry, I missed your comment when you posted it. Please go to the forum page, Bras section for a full reply
Corset Hugs

Hi there Zeeshan,
Let us know exactly what bits are foxing you, and we'll see if we can offer any advice to help you out :-)

Lovely article!! Inspiring & informative.

I'm a very curvey girl with boobs to match, 40N. I can't find any bras to match in the UK. There are the custom made variety which start at £250!! So I have been looking for a pattern or a miracle (lol).

The additional problem is even though I'm a curvey girl, I have a small back but humungous breast. So custom fitting is the only option.

I have been looking at some patterns on the net but they only go up to a K. I did block/pattern classes last year, so I'd like to make my own bras. Know it may be difficult at first, but I'm up for the challenge.

Can you recommend any books or do you have any advice?
have any advice, it would be greatly appreciated.

Hey there, I absolutely love this tutorial and have come back to it multiple times. But there's something that bugs me every time I read through it: The "old bra sizing method." The method of adding 4-5 inches to your underbust to find your band size is outdated and leads to over 80% of women wearing the wrong bra size, the majority of problems being that she's wearing a back size too big and a cup size too small. You band size is the nearest whole even number! Of course, depending on "squishability" and comfort level, this can vary, but telling people to add huge numbers to find their band size has lead to a serious difference in bands across brands, especially in the U.S.
For example, I have a 27.5" underbust, and a 34" bust circumference. By the "old method," I would be a 32B, which is what I used to wear. I spilled out of it in the under arms and tops of the cups, the band would ride way up on my back, and everything was uncomfortable! In reality, my starting point is a 28E. :)

Hi savvy,
Yes, the “old” way of measuring for bras is in a mess that’s the reason I instruct people to use there over breast and breast root to breast root around the back for drafting.
Corset Hugs.

Hi Mark,
Yes, and I'm very glad that you instruct us to use exact measurements. Sorry if I sounded angry, it just pisses me off so much that almost every bra calculator out there uses the "old way." I live in the U.S. and this country is so behind on extending beyond 32-38 A-DD sizes! So I'm automatically irked when I see the "old method" and can go on an angry rant sometimes.

I've used your tutorial for multiple projects and have found it very helpful and am very grateful that you created it. The only issue I have is changing the cup shape. I have wide and shallow breasts, where I find the pattern to be for narrow and projected breasts. But luckily I have plenty of years of sewing experience, and this is definitely a good place to start. Maybe addressing different shapes can be an extension of the tutorial one day? :)

Thank you for your reply and I hope many more people will find a passion in sewing their own bras, or at least learning about proper fit, size, and shape. :)


With the 'fashionable full shape'.

If a woman has perky breasts, I think she would be able to stick with the above instruction and come up with a well-fitting bra, although I personally think all undergarment measurements should be done naked.

However, if she has saggy breasts, I think doing the root-to-root measurement without a bra while bending over with the torso parallel to the ground would give a workable measurement that mimics the height of a fashionable full shape.


Hi Jelena,
Please look at the forum under Bras. Not enough space in the comments section for my thoughts on the subject.
Corset Hugs

robin cogburn

just found your site. I'd love to explore altering bra sizes for when cute garments no longer fit!

robin cogburn
can't wait to explore your website!
Great information. Thanks for sharing the tips I will definitely refer back often.
Great read! Looking forward to the next part.laugh
Find the comments and answers very interesting. There is a revolution a-comin'.
The math isn't a problem. Measuring could be. There are 2 situations. With the back parallel to the floor, breasts hanging, they either form a "spherical cap" (the largest diameter is at the chest) or a hemisphere and truncated cone. The latter is easy to measure. 1) Circumference at the fullest part, 2) distance from the fullest part to the chest (perpendicular to the chest), 3) circumference at the chest. The volume for the hemisphere is 1/2 that of a sphere. See: https://en.wikipedia.org/wiki/Sphere. For the truncated cone, see: http://www.aqua-calc.com/calculate/volume-truncated-cone

The spherical cap shape will require special measuring equipment. The measurements are the maximum distance from the chest to the tip of the breast and the diameter of the circle at the base of the breast. The math is here: https://en.wikipedia.org/wiki/Spherical_cap.

Note: any place that calls for a radius (r), divide the circumference by 6.28, or the diameter by 2.

Email for help.

Having not seen that many breasts hanging, I may have oversimplified. The circumference could be the same all the way down, in which case it's a cylinder and hemisphere. Or the largest circumference could be at the chest but the breast not tight to the chest, which is still a truncated cone and hemisphere, but with the larger radius at the chest. In the latter case it's a judgement call where the curve of the hemisphere starts.

I wish I could enter diagrams to make this all clearer. Please contact me if you would like drawings.

Pamela Bowman
I just discovered your wonderful blog which i plan to read thoroughly. I have several panty patterns to try first before attempting bra making. Like most other women, finding a bra that fits is nearly impossible and i hate to try on bras in a store. The bras i have seen other sewers post are much nicer than the usual bras sold in stores. The custom sewn bras that people make rival the custom brands that are too expensive for the average pocket book. It makes sense to learn to make lingerie.
This is the perfect tutorial for me! I have a reasonably full bust and it seems there's some sort of unwritten rule that I'm not allowed to wear pretty, lacy bras... because shops don't sell them in anything larger than a C up! I have wanted to make my own for so long but couldn't find a sewing pattern anywhere for the style that I want so I'm going to attempt to make my own!
So wheres the template?
Foundations Revealed
Hello Laura,
Which template are you referring to?

I would really like to see the next parts to this, however, this appears to be blocked, one cannot go to the next page without registering, but you are no longer accepting registration..

Obviously I can understand that you may want to concentrate on local classes, but for those of us on the other side of the world, could you please provide access to your existing pages on this?

Foundations Revealed
Hi ,

The next two parts of the article are available for free. Try these direct links instead:

yes! you can click on them and it will bring you to where you can buy it.

Kenneth Harvey
Don't ask me how I managed it but somewhere along the line I managed to mix up imperial and metric and managed to make a bra suitable for a gnome with one B cup and one D cup.

I started doing this as something out of curiosity with no end game other than a learning experience. And I guess I learnt not to mix up the two measurement systems. At least I hope I did, I guess I will find out tomorrow when I make a coat that shouldn't have tails but may end up having a waist length back left and an ankle length back right if my attempt at a Bra is anything to go by.

Go me.

Robin Burdett
Thank you! Great information
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