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| From top to bottom these bras have the same cup volume: 38E, 36F, 34FF, 32G, 30GG, 28H |
The relationship between band sizes and cup sizes is something I explain most frequently. The common misconception is that all cup letters are the same size of boob on different band lengths. So, for example, people assume that all women with F cup boobs have the same size boobs regardless of whether they're a 30F or a 40F and this simply isn't true. A lady with 40F boobs is actually five cup volumes bigger than the 30F lady and that's because when the band size gets bigger it increases the volume of the cups.
Sister Sizes is a phrase that refers to bras that all share the same cup volume but have different band lengths. For example, a 34E and a 32F are sister sizes because when you go one band size down from a 34 to a 32 you have to balance the size by going up one cup from an E to an F cup to keep the cup volume the same.
Click Here to read why all D cups aren't the same and Click Here to read why cup volumes increase as the band increases.
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| These bras all have the same cup volume spread out over different length bands. From top down: 28H, 30GG, 32G, 34FF, 36F, 38E |
Because a picture speaks a thousand words I wanted to show you what sister sizes look like and how the proportions change. In the picture above the six bras shown are the following sizes from top to bottom: 28H, 30GG, 32G, 34FF, 36F, 38E. All of these bras have the same cup volume, however, their band lengths and proportions are different.
You can see that the band on the 38E at the bottom is the longest band so the woman who wears this bra needs her band to go around more torso than the woman who would wear the 28H bra at the top which has the shortest band. Proportionally the 38E lady will look like she has a smaller bust because her bust volume is spread out over a wider torso. The 28H lady will look like she has a larger bust because her breast volume projects further forward on a narrower torso. In reality they have the same volume of boob but it is spread out over different areas of chest/torso.
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| From top to bottom these bras have the same cup volume: 38E, 36F, 34FF, 32G, 30GG, 28H |
The Proportions
While the picture above is helpful to show that the cup volume on these sister sizes is the same what it can't show very well is how the proportions differ. You can see that the bands on the 30GG and 28H (bottom two bras) are deeper and have more hooks than the other sizes. This is because the volume of a 30GG and 28H bust projects farther forward than the volume of a 38E bust (which is spread out over a wider area so doesn't project as far forward) so the band has to be stronger to counteract the projection at the front.
Besides the deeper band and more hooks you may also be able to see that the wings are darker on the 28 and 30 bands than the 38-32 bands and this is because it's double layered to give more support. The wing has to be reinforced as there is less length to disperse the weight of the breasts over. The longer the band the greater the area the weight of the breasts can be dispersed over. This is the reason longer bands don't need to be as deep or firm as the shorter bands.
The proportions of the bras differ in the following ways (you'll notice that the gore width decreases as the band length shortens and this is because the breast volume is gradually narrowing in width and increasing in projection).
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Band
Length
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Wing
with Hooks Length
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Wing
with Eyes Length
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Wing
Depth
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Gore
Width
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38E
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29”
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6.25”
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8.25”
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4.5”
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1”
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36F
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28”
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6”
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8”
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4.5”
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1”
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34FF
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26.5”
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5”
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7”
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4.5”
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3/4”
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32G
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24.5”
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4”
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6.25”
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4.75”
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3/4”
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30GG
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23.75”
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4”
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6”
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4.75”
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5/8”
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28H
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22.5”
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3.5”
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5.25”
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5.25”
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5/8”
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Bra Science Vs Bra Reality
I wanted to explain this bit of bra science to further help you understand why cup sizes mean nothing without knowing the band size. In reality good bra fit is affected by things like brand, body shape, age, height and bra style. It's great to know the principles of bra science but remember that when a bra fits you well and you are comfortable that's the most important thing. Leave a comment if you need something explaining more xx
N.B: The bra used in these diagrams is Tango Beige from Panache Superbra
Excellent visual!
ReplyDeleteI'm very curious how wire width changes? It seems that there are some difference, but how much it changes from size to size?
The wire width doesn't change as much as the wire depth changes. That's something I will include in my next post on this subject for sure! The distribution of the breast volume is so important because that's when we get into breast shape and suitable cup shapes. Who knew bras were such complex little beasts! xx
DeleteI'm really looking forward for this post!
DeleteI always wonder how things change between sister sizes. Thank you for this post and the planned one!
Fantastic post! LOVE this so much! A great explanation of how different cups vary on the band size, and an easy explanation of sister sizing.
ReplyDeleteThank you Amber! I needed this kind of enthusiasm today so a big hug to you!! xx
DeleteClaire, I posted about your blog post and linked to you. Hope you don't mind I used your photo (I credited and linked to you), I just love this article so much I HAD to share it with my readers! Let me know if it's okay if I keep the photo on the post. Thanks! :)
DeleteIt's TOTALLY OK Amber! I'm glad you found it so useful, hope your readers do too xx
DeleteThis is amazing !! I never understood this concept before seeing it visually like you've done. THANK YOU!
ReplyDeleteYou're so welcome Hopey (I should have got round to it much sooner!) I'll work on some more visually explanatory posts as they seem to be a good reference point for lots of ladies xx
DeleteI wonder if the deeper wing in the smaller band sizes is also because that way the total area of band stays about the same as in the bigger band sizes. So the pressure applied to torso stays the same.
ReplyDeleteYou're right that it's to do with surface area and pressure. The wings on shorter bands are such an important part to give women with small torsos and heavy breasts some comfort. xx
DeleteThis will be a great additional resource for explaining things to people. It's the other side of the "D cups" image which I've pointed a good many people to.
ReplyDeleteThank you for sharing AE! I'm gald these images are helpful. We'll definitely put more of them together. xx
DeleteSo, I'm curious. How would I find out the sister sizes for my size (44DDD)? I am curious if a sister size might fit me better!
ReplyDeleteHello Rachel - Sister sizes work this way. For every band size you come down from your current size you add one cup letter. And for every band size you go up from your current size you come down one cup letter.
DeleteThe sister sizes for your 44DDD are as follows: 42FF, 40G, 38GG, 36H, 34HH, 32J
Going up in the band, the sister sizes are 46E, 48D, 50C, 52B, 54A
Your best starting point is the sister size that is closest to your ribcage measurement. Wrap a tape measure around your ribcage where your band should sit (make sure it's parallel around your body) then choose the size that is closest to this band measurement. Once you get your band size right you may find that you need a larger cup because your boobs are in the correct place (higher on your body). So for example, you might try the 38GG then find that you need a larger cup so you'd move to a 38H.
Hope this helps! xx
This does help! Thank you!!!
DeleteThis is such a great visual! While I understand the concept of sister sizes, it's sometimes difficult to picture. Thanks!
ReplyDeleteThanks BBB, glad you found it useful xx
DeleteHi,
ReplyDeleteI want to say how THRILLED I am to have found your site/company. I am a natural 32F and I live in a very small city. My only options here are very expensive French-made bras (which I do really love, but $249 a pop's not really in my budget these days) and so to find your Canadian-made Panache bras and have them arrive by mail, from a Canadian site, with a perfect fit, and so pretty...it made my week! I will return! Thank you so much for providing us boobalicious Canadian girls with a great option!!!
Well, this is just about the greatest comment we could ever hope to have! Thank you! I'm so glad you like the service. Canadian women have had the short end of the bra stick for a long time so we wanted to make it easier and more fun to be busty in Canada. Panache is actually British but our business and focus is Canadian :) xx
DeleteThank you for this post--it has helped explain some of what I think is one of my main bra fitting problems. I am extremely short-waisted (seriously, no torso to speak of), with breasts that are set up very high (practically jutting out of my collarbone), but also stick out past the sides of my body. So, they're best described as "wide," I guess, with a lot of breast tissue over at the side near my arms, but yet not any breastbone showing between my breasts.
ReplyDeleteThe issue I'm having is that I've been wearing 34FF, but I have to go to the tightest hooks within just a week or two. I should probably be wearing a 32G...but no matter how much people keep telling me that 34FF and 32G are sister sizes and should fit the same, I swear that a G cup just comes up too high under my arms, to the extent that it pokes me in the armpit and actually rubs against my upper arm all day. (I'm middle-aged and probably a bit more bingo-winged than many of the younger bloggers.) But if the wings of a 32G are 1/4" higher than those on a 34FF, maybe that it explains it? A quarter-inch isn't much, but maybe it's enough that that's what's causing the cup of a 32G to just come up too high for comfort.
In any case, I will look forward to your explanation of wire depth comparisons, since that may help, as well. In the meantime, I'll just keep tight-hooking my 34FFs, since I'd rather tight-hook and get less wear out of a bra than be poked in the arm all day. Anything is better than the slide-up-my-back 36DDs I wore for years.
You are absolutely right that the proportions of the 32G are deeper in the wing and 1/4" can make the difference between comfortable and 'pokey'. You can combine a 32G fit with comfort by looking for styles with shorter wings. Claudette is a brand that I think you should look at because the style works brilliantly on women with high breast tissue as their wings are much lower. It sounds like you have your size range sorted out you just need to pair that with the right style and you're on your way to best fit. We have just this second posted a video about this on our YouTube Channel
DeleteI'm curious about how the depth of the cup varies from size to size. I wear a 34F as a general rule in Panache bras, but the Tango is one I have never been able to fit into.
ReplyDeleteWhen I try a 34F Tango, the wire width is perfect, the cup depth is great, but the back is too loose, so I don't get enough lift, resulting in a saggy profile. If I tied the back in a knot, the Tango would give me a lovely shape!
If I sister-size to a 32FF, or even a 30G, the wire is fine in width, albeit slightly deeper under the arms, and the back is much, much better - but the cups themselves are deeper than on the 34F... so I don't fill out the cups, and again, I'm rendered saggy-looking.
If I size down to a 32F, the wires are too narrow and sit on my breast tissue, but the cup depth is better, giving me a better shaped profile.
So I think ideally, I would have the cups from the 34F mounted on a 32/30 back. The crucial thing, from my experience, (and I find this with Freya and some Curvy Kate too) is that the cups on a 32FF are deeper than the cups on a 34F. So, surely that means the volume isn't the same?
I understand that the Tango probably is a style that just doesn't work for me, but I think its often easier to spot differences in construction when judging between two bad fits - because you're looking at the bra itself, not distracted by awesome-looking boobs.
These are the finer points about why sister sizing isn't really a fit solution because the proportions change so much. The Tango definitely isn't the style for you. The volume equivalents are never identical however, the principle is there to explain why we have much more than four cup volumes. Breast shape is a crucial factor for sister sizing too. It sounds like you may have a wide breast volume that has less forward projection than the dimension of a 32FF is looking for in some styles. xx
DeleteIf you are comfortable with your sewing skills, you could try altering the band length. It isn't that hard to do and there are some wonderful tutorials out there. I believe www.reddit.com/r/abrathatfits have some great links for it as that's where I started out and found a few of the tutorials.
DeleteThanks for posting this. It helps me to understand that my breasts have gone down in size with my weight loss. I've lost 45 pounds and gone from a 42F to a 36F. My boobs swim in my old 42F cups, even though it's the same letter size.
ReplyDeleteThis is a PERFECT example! You can see that even though you're still wearing an F cup the volume is much smaller because you've come down three band sizes and therefore three cup volumes. Thank you for sharing this example! xx
DeleteSoooo good! It's a really great visualization, and obviously a lot of people appreciate it. :-D
ReplyDeleteI'm really happy the images have helped lots of ladies see the relationship between cups and bands xx
DeleteWhat a great visual way to explain this! I am sick to death of people saying "oh but your not an E cup, look at you, your far too slim..."now I can send them this link :)
ReplyDeleteI'm so glad it's useful! It's so common for people to say "you don't look like so and so cup" when in fact you can look like all sorts of cup sizes, it just depends on the band!! xx
DeleteI have discovered that sister sizing does not work for me in Cleo Lucy. I fit very well into 30GG in Lucy. However, I find that the band is too stretchy for my just slightly upwards of 28" ribcage (I bought the bras before I lost a bit of weight). So, the next Lucy I bought was 28H and the fit was rather poor. It didn't poke me anywhere, didn't look visibly larger or anything. But it gave me an in-cup quadraboob at the horizontal seam, and I could definitely take the cup in at the seam if I was up for a project like this. So, sadly, I returned this bra and bought another one in 30GG. I'd rather take in the band when needed than the cup! Which makes me quite weary of advice to go up/down in the band - it may not fit the same if you do, sister sizing and all.
ReplyDeleteSister sizing isn't necessarily advice for finding fit, it's more a guide to understanding that cups and bands are related to determine size. It definitely isn't a hard and fast rule that you can go up and down the sister size scale and fit or be comfortable in each size. Whether the sister size scaling will work depends very much on the cut of each bra and your own shape. The proportions of wire depth and curve will change as you sister size up or down so that probably explains why the fit of the 28H wasn't right for you. You're right that altering a bra band is far easier (and preferable) to altering cup shape and volume dispersal. xx
DeleteGreat post! I just have a quick question. I struggle with finding my 'best fit'. My rib measures 29" and if I wear a 28H my boobs are happy in the cups, but I find the band feels a bit tight. So sometimes I wear a 30GG instead but even then can find the band still tight. Am I doing sister sizing right? If I want more room in my band of a 28H, what size do I try? Thanks so much for your help!
ReplyDeleteKind regards
Becky x
Hi Becky - You are doing sister sizing totally right. The next logical size to try for a looser fit from a 28H is a 30GG (an then a 32G) and this will often depend on the brand or style of the bra. Some bras are considerably tighter than others. It may be the cut of the bra too. Some women find that bras with shallow bands feel tighter than those with deeper bands because the direct pressure to their ribcage constricts breathing or just feels painful. Remember that some styles will never fit you (this is true for everyone) so if you can't get comfortable not matter which size you try then it's most probable that the style is wrong for your shape. If you happen to love a bra and want to break it in then a bra extender is always a handy thing to have at the back of your bra drawer. Hope that helps! xx
DeleteWhat a great article. I have always stayed true to my size. If I couldn't find it I wouldn't buy the bra. I am very funny that way. But know I understand a lot better.
ReplyDeletei wear a 38J. the band is perfect. super comfortable, no riding, lots of support. BUT the underwire is poking me under my arms. i think they're too wide. i have a freya, a change, a rosa faia and 2 different goddesses. they all have the same problem. i think i need a narrower or shorter wire and a deeper cup. is there such a thing? i just ordered some Ks to experiment, same band size. any thoughts?
ReplyDeleteHi Barbara, if you are petite then you may very well need bras with a shorter wires. Styles like Eva by Elomi have been designed for heavy bust petite women. If your 38Js fit you well in volume but are too deep at the sides then the length of wire is essential to perfect your fit. xx
DeleteI hope you are still watching this comment section...
ReplyDeleteWhat about wide-set breasts? According to everyone that measures me I wear a 34E. But my breasts don't go in a 34E bra; tissue is squished out the top, out the sides and under my arms while the cup itself is half empty. If I go up a few band sizes and down a few cup sizes to, say, a 38C the fit is much better in the cups but I have to seriously take in the band (which is not possible on many, many bras). Are there manufacturers who provide bras for wide root breasts with almost no projection?
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ReplyDeletelandlasider