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A 32B has the same cup size as a 34A?- How Bra Sizing Works

Miranda Kerr

While it is assumed that nearly all men don't know how bra sizing works, do you know that as many as 80% of women get it wrong too? 

This may come as a shock to you but two cups of the same letter are NOT the same. A 32B and 34B does NOT have the same cup volume. So if you didn't know that a 32B has the same cup volume as a 34A (and a 30C for that matter), then please read on. (Note: I have included a band size conversion chart at the end of this post if inches isn't your thing.)

Wearing the right bra size can (almost) make your boobs look as great as Miranda's

You may know how to calculate your bra size, but it's important to know the "bra matrix" too. That is, how different sizes are related to one another. This is important to know as the fit can differ between manufacturers. Even if you've measured yourself, you might still find yourself wearing a different size for different brands. Knowing how the bra matrix works allows you to quickly figure out what size you need to move up or down to when trying bras. 

Let's start with the golden rule: Cup size is RELATIVE to band size.

 They're both DDs but they definitely do not have the same cup volume! Photo: stanikomania

That's right- you can't just look at the letters. If you usually wear a 32B but there is only a 34B in store, do NOT reach for it thinking it will fit if you clip the band at the tightest hook. They aren't the same! How big a cup volume is depends on the length of the band. Here are a few practical scenarios that you may come across when trying a bra:

Scenario 1: The band fits, cup doesn't

Things are pretty simple if you find the band fits. If you need a bigger cup, just go up a cup size (e.g 32B to 32C): and if you need a smaller cup, go down (e.g to 32A).

Scenario 2: The cup fits, the band doesn't

Now THIS is the complicated part where the bra matrix comes into play.

Rule 1: If you need to go down a band size (make it tighter), you need to go UP a cup size to retain that same volume e.g If you try a 34B and the cup fits but the band is too loose. You should try a 32C for the same cup volume with a tighter band.

Rule 2: If you need to go up a band size (make it looser), you need to go DOWN a cup size to retain that same volume e.g If the 34B fits in the cup but the band is too tight, you should try a 36A.

What does that mean? It means that 36A, 34B, and 32C all have the same cup volume, but with different fitting bands. This equation is known as the 'bra matrix'. So depending on the brand and fit, you may have as many as 3 different sizes in your closet! But they will all fit the same!

Now that you know it's all relative, don't get too caught up on cup size. A lot of bigger women actually need a tighter band and larger cup size but they're just too afraid to face that bigger letter (when really, it's the same cup volume!). Just the same, women with small busts might be afraid to go down a cup and try to squish themselves into a smaller band size just to get that 'B' or 'C'. Don't do it! Wearing the right size will provide your bust the right support and boost it needs. Going up a band size and down a cup size might actually make your chest look bigger than the bigger size!

To reiterate:
– Down a band size, up a cup size
– Up a band size, down a cup size

Silly way I remember this rule is to put it in the context of a bunch of band members with a set number of drinks (cups) at their party. If less people attend than expected, there will be more cups to go around. If, on the other hand, there are more people- there will be less to have.

In a nutshell:
– Down on the band numbers? Up on the cups!
– Up on the band numbers? Down on the cups!

SCENARIO 3: Nothing fits!

Well, it's not rocket science. If both the band and cup are too tight, you need to go up in both e.g 32B to 34B. On the other hand, if it's all too loose, go down e.g 32B to 30A. Keep making adjustments till you find the right fit.

How should a bra fit?

  • A new bra should fit on the LOOSEST (outermost) hook. If you find it's too loose on this hook, go down a band size. As with all clothing, bras will lose their elasticity with wash and wear. The other hooks are there so you can tighten the band as this happens and keep getting a good fit. If you get a new bra that fits only on the tightest hook, you have nowhere to go from there! (Obviously the exception is if you're even smaller than the smallest band size).
  • Cups shouldn't be gaping (if they are, go down a cup size) and neither should your breasts be spilling over the top or sides (go up a cup size if they are).
  • The band should be sitting flat against your skin- it should not be riding up at the back or front. Do not tighten your straps to compensate- get a smaller band instead! The support should come mostly from your band, not your straps. 
  • You should be able to run a finger under the straps and band. It shouldn't be so tight that it leaves red marks on your skin after you take it off.

How to calculate your bra size:

Lastly, I thought I would add the basics just in case some of you don't actually know how to measure yourselves:

Band size:

Using a soft measuring tape, measure your underbust. The tape should be taut against your skin and you should be standing tall and exhaling slightly. Round up if you get a fraction. This number is your underbust measurement.

If your underbust is an even number, add 4 (e.g 28 becomes 32). If it's an odd number, add 5 (e.g 31 becomes 36). This final number is your band size.

Cup size:

Next, measure the fullest part of your bust. (You should be braless or wearing a soft cup bra- no padding!). Don't pull the tape as tight as you did when measuring your underbust- you shouldn't be squishing your boobs! Then, subtract your band size from this reading. If there is no difference or less than one inch difference, you are a AA. If there is 1 inch difference, you are an A. If 2 inches, you are a B, If 3, you are a C. If 4, a D…and so forth!

Band conversion: 












27-28 inches










29-30 inches










31-32 inches










33-34 inches










35-36 inches









Note that some online charts claim that a US and Aussie cup sizes runs one size bigger than UK/French/International sizing e.g a US32A is the same as a Au10AA. Personally, I have not found this to be true at all. I would say a UK32A is an Au10A.

I guess the problem with the bra world is that there really doesn't seem to be an industry standard. You can measure yourself and get your right bra size and something might still not fit in reality. So make sure you understand the bra matrix well so you know how to move up and down within the same brand. And if you're ordering online, then at least you know what size to exchange for if something doesn't fit. Another thing is to always remember to always check out each brand/website's own fitting guide before making a purchase as it can differ from one another (or get yourself measured if you're at a physical store that has a fitting service).

Hope this post was educational for you! 🙂

UPDATE (19/06/2014): I really appreciate all the comments which have come in, but I have decided it is time to close it as this is an old post. If you have a question, I think it's best you ask a professional, or your trusty friend Google. You can also scroll through the old comments and see if there is anything there that might help you. I wish you all the best in your quest to finding the perfect bra! Thanks for taking the time to read this post and I do hope it has been helpful.

Related post: How Do Bra Extenders Work?

64 thoughts on “A 32B has the same cup size as a 34A?- How Bra Sizing Works

  1. Thank you, that was much informative…exactly what I was looking for..actually I'm in a bit of confusion regarding my size as I've just put on some weight!

  2. 32B is small in cup and band.
     I can't buy 34B because it's out of stock. What should I get. 32C or 36B? what is difference is gonna make each ways?

    1. Hi! If you really had to I guess you could go for a 32C with a bra extender. A 32C has the same cup size as a 34B and that’s the most important thing! If a 32 band is way too tight you could also try a 36A which has the same cup size as a 34B with a much looser band. A 36B is a cup size bigger than 34B so no point there…unless you really do need to go up 2 cup sizes. Depends on how small the 32B is on you. I hope that makes sense, it can be very confusing I know!

  3. I tried a 32a the cup was perfect but the band was too small.  I was told that my size is a 34a but the cup was big and the band fit perfect.  What size would you recommend? 

    1. You’d be a 34AA. I know AA cups are hard to come by in many countries, so you can also try a bra extender with the 32A. You can get them very cheaply from eBay and they save a ton of hassle- I love using them. Eventually all bands loosen anyway so you won’t need to use it forever. Hope that helps!

    1. So sorry for the late reply. Does the 34A cup fit well since that is a bigger cup size than 32A? If it does and you still need a bigger band, try a 36AA or use a bra extender. They are a lifesaver!

    1. I’d always recommend trying to wait it out for your size if possible (or trying another store/brand?) as obviously nothing is going to fit better than that. But if you need something new urgently, you can try a 32B with an extender.

  4. Please help:-) I was 32C, which used to fit perfectly in Wacoal and VS bras, but i lost weight and need to go down a band size. Cups fit well still, but the 32" band rides up the back and it's a pain in the butt to always pull it down.I went down band size and up a cup size, per your article:-). 
    So, I tried ordering regular and strapless in 30D (also from Wacoal), and the 30" band fits great, but the cups were too small and squishing my boobs. I can't possibly be a DD? I've found some decent FREYA bras in 30DD but afraid they won't fit. I measured myslef and it seems like I'm between C and D but these cups don't fit me (too small) once i go down to 30" band. I'm super confused. We also live in a little town with no boutiques or measuring services around, haha. Maybe you have some advice on this issue; Thank you!

    1. Ordering online is always going to be a bit of trial and error I’m afraid. If the 30D cups are definitely too small, I think it’s logical to go up a cup size- but stick to Wacoal as that’s what you tried. Different brands can fit differently, which is annoying but unfortunately reality. Sometimes you may find you are different sizes depending on the brand. So stick to what you know if you want to avoid going back and forth too much 🙂

  5. Hiyaaah. I tried a 32b but the band is quite tight and the cup is slightly tight too. What should i do? What bra size should i try on next? 
    Thanks 🙂 x

    1. Hi, I’d try a 34B- it is a band size and cup size bigger than 32B. If that cup fits okay but you need to go up another band size from there (since you mentioned the 32 is quite tight), try a 36A.

  6. hi,. I lost some weight this recently,and 32B bra used to fits just perfectly. Now, 32B cup is still fine except that, the band seems loose-even on new bra. I tried 32A but it feels so tight-makes me suffocate. and 34A is just too loose. what size would you recommend me.. tq 🙂

    1. Hi, If the 32B cup fits fine and you needed to go down a band size, technically it would be a 30C…but I am confused by you saying that the 32A is tight. Do you mean that the 32B band is loose but the 32A band is too tight? That should not be the case if they are both 32. Are you trying on the same brand? Sometimes different brands fit a bit differently.

  7. Hi! So I have 1 bra that I own that fits (sad, right?) my mom won't get me any more because she says the other ones I have fit, but they are too small (I'm 13, I grow, ya know?) but she just won't get me any more. It is a size 32B and it fits really well (I don't really know what brand though). Anyways my sister got a bra, a 34B and its a really nice one, but it doesn't fit her so my mom gave it to me. There is a problem though, the cup fits fairly nice (a tiny bit big if anything) but the band is really big, like it fits but I had to make my own hook beyond the ones they had made. I know that's not good. What should I do? Try to convince my mom to get me more? Or live on with the one I have? Or try to make the other fit?
    Thank you!

    1. Hi! I know it may be tricky but you really do need to convince your Mom that you need good fitting bras. I wouldn’t recommend modifying bras unless you really have to as obviously wearing your correct size will give you the best support that you need. Would you feel awkward showing your Mom how your other bras don’t fit? She really does need to understand that as you do need more than one good fitting bra now that you are a young woman. Maybe it would help if you let her know you would be happy with something that is affordable? I wish you luck! 🙂

  8. So I have this problem and I think I know the answer but I am not sure. So for the past say six years I had been wearing a 34C because the cup was the perfect size but I had never been fitted before; till this last summer and they told be I was a 32C but whenever I put on a 32C the cup size was too small and my boobs didn't fall out but it definitely didn't fit but the band fit better than my others. Little did I know I had been wearing a bra wrong up till a few moths ago.(I just turned 19) i thought it should always be on the tighter most hook, I was wrong. Anyway, my problem is that every time someone at stores size me they say 32C but when my friends and I did it on our own everyone else got their size except me. Every time they measured me they got 32D, but places like Victoria Secret told me otherwise. And according to this page I am a 32D as well. Is this possible or am I delusional? A 34C cup fits but is too loose around my body but a 32C cup is too small of a cup but fits my body. I have tried a 34B too but the cup is too small as well. Help?

    1. More than happy to confirm that you aren’t delusional. It does sound like you are a 32D since the 34C cup fits well. If a 32C doesn’t fit, then it doesn’t, no matter what the tape measure says!

      Personally I think different bras and brands can fit differently so I don’t think you should get caught up in saying you are one particular bra size. The bra you get should be the one that fits!

    Hi, my bra size is a 32B, I've been a 32B for as long as I can remember, but I went into Victoria Secret not too long ago and they measured me and said that I am a 32C or 34B. So I bought 34B bras and the cup size was good, but the band was too loose so I put it at the tightest hook and it fits me perfectly. So I've been confused on wether what size I am because I have 32B and 34B bras and they all fit me good, I also measured myself and I am a 32B. And I also recently ordered online a 32 C padded bra because I thought it would be slightly smaller than the 34 B, do you think that would still fit me?

    1. Hi, apologies for the delayed response. It does sound like you are a 32C at Victoria’s Secret as that’s a 34B cup size with a smaller band. A new bra should always fit on the loosest hook so the 32C sounds perfect for you. Just keep in mind that different brands can fit differently though (just like clothes). So you may find you are a 32B with one brand and a 32C with another.

  10. I've tried on about 40 bras today. Nothing fit, from 36A, to 34B, to 32 or 30C (the 30 and 32Cs fit the best cup-size, but band size, they were too tight). My breasts are kinda narrow and wide set yet you can see my ribcage for 1/2 to 1" on each side towards my armpits, so my ribc age is too wide for my boobs. It's so frustrating. I bought a 34B but it's a bit uncomfortable – tight on the bottom of the band, though the rest seems to fit well enough. Should I just keep it and get a bra extender or wear it to stretch it out or just return it? 

    1. Hi, sorry for the late reply. I’m sorry to hear bra shopping has been so hard for you. It can be a very frustrating journey indeed. Have you tried different styles? Just wondering whether a balconette or plunge bra might suit you? Or something with padding on the sides? Front clip bras? In your case since you have found a 36A does not fit well then I would say stick to the 34B and add a bra extender. Eventually with regular wash and wear it will stretch out anyway and you can ditch the extender.

  11. Hi so I have been a 32A for as long as I can remember but I haven't actually been properly sized.  My breasts are falling out of all of my bras and the band is a bit too tight. 

    1. Hi it sounds like you have outgrown your previous size. I would recommend getting measured or trying on some bigger sizes to see what fits as it is quite important for us women to wear a good-fitting bra 🙂 Probably start with a 34A and make adjustments from there. Good luck!

  12. I am going foe breast enlargement a 32b is it posable that you can send me a example of a photo please.  Thanx Carol.

    1. Hi, you can easily find photos on Google, especially on plastic surgeon websites. Try Googling something like “(enter the size you’re after) breast images”. I hope you’re doing it for yourself and will be happy with the outcome.

  13. Hi,
    I had a baby about a year ago and recently started buying new bras. I haven't had a fitting but I bought 5 bras from Victoria secret and have to ship them back because the cup size seems too small. I wear a 34b and the band is right but I need a cup or 2 larger. Would I go for a 32c?
    Thanks! 🙂

    1. Hi, you should go for a 34C. If that’s still too small, then try a 34D. I hope motherhood is going well for you 🙂

  14. Hi i was a 34B ,all the bra's became old and the straps would keep falling off my shoulders ,i thught time for a new bra and then i measured myself and found i have become a 34A .but i am not finding this size in almost 90% of the brands in india (and even if i found the bras were too expensive)  so shall i try a bra extender , i have some 32B size bras with me ( i read one of the questions here and you suggested a bra extender and she was the same size as me 34A)

  15. Hi can you clarify something for me???i measured today again underbust is  31 inches and overbust is 35 inches ,so is it 34 A or 36 A ,new bra in 34 B fits well in band but cup doesnt fill in well ,so i thought i could be a 34 A 
    now i am totally confused!!

    1. By your measurements, you are a 36A…but don’t get too caught up with being a certain number because like I always say, different brands/styles can fit differently. To me, measuring kind of gives you a starting point and then you should make adjustments according to how the bra you’re trying fits. In your case, you should definitely try a 34A, but stick to that same brand/style.

  16. Hi! I was set on buying this one bra, then they ran out of the size 32b, which is what I've found to fit the best. In the reviews they say that the bra runs small, so what size should I get since my size is out of stock?

    1. Hi, so sorry for the delayed response. Are they planning to restock your size? If not I would probably recommend looking for another bra, as hard as it is to walk away from a something you like. Ideally you should try to buy a bra in your right size- nothing else is going to fit better. Does it run small in cup or band? You could experiment with other sizes- 30C, 32C, 34B etc..but if a 32B fits best, then ideally you should stick to it.

  17. Hi, so ive been  34b for a while now, and been wearing them on the tightest hook for 3 years and now I lost almost 10 pounds and the cup size is to big, and im guessing the band size is to. so what size should i go down to? what size down from a 34b, and a band size down?  

    1. Hi, a cup and band size down from 34B is a 32B so give that a shot. It may also be that your 34 band has just become loose with wear so if the 32B band is too tight, try a 34A. All the best!

  18. Hi sorry for late reply. thank you although i didnt find 34 A and 36 A was too loose i ordered for bra extenders and will use them with the 32 B bras 🙂

  19. I have been a 32 B but I got measured at Calvin Klein and the nice lady told me I was actually a. 30 B. But I didn't have time to try on smaller sizes or cups. I'm so confused. When I wear 32 B it only fits my band and breasts when it is at the tightest. I know that shouldn't happen… What sizes could I wear? I'm trying to figure it out but I don't know how to because I am confused with your explanation at the top. If I am a 30/32 B and the band needs to go down, what size would work for me…?
    please help, going shopping tomorrow for bras..

    1. Hi, it does sound like you are a 30B. Going down a band and cup size from a 32B is indeed a 30B. Since you were also measured to be this size, I would make it a starting point when trying bras. I hope that helped. Do let me know if you are still confused!

  20. I purchased a 34A bra and was very happy because I fill the cups out pretty well and it felt like a snug fit. I am a little sad however because there is LITTLE space between my breasts and the bra's edges in the middle (basically the parts that curve in the center of the bra, if that makes sense) it is not a lot of space but i've heard that there should be NO space at all. NADA. Does this mean I am a 36AA? Also the band I believe is tight and I know it's not the cup size because of the gap between my bra and breasts. Can I just continue to wear a 34A with a bra extender? Thanks! 

    1. To me, that actually doesn’t sound like a really bad fit. You just want to make sure the cups are not gaping at the top and the middle of the bra is sitting relatively flat against your skin and not riding up. Do you feel you get enough support from it? If AA bras aren’t hard to find where you’re at, you could definitely give a 34AA a shot just to see how a smaller cup fits (and wear that with a bra extender if you feel the band is too tight). Sometimes, it could also be the style of the bra not fitting the shape of your breasts. Hard to tell until you experiment. If you feel you are quite happy with the 34A and its doing its job, personally I would stick to it, only because I know that AA bras can be hard to come by.

  21. Can you please guide me if band size is 32 than length of 32 band bra when measured by measuring tape should also be 32? I bought 32b bras of two different brands. Length of one bra when measured from bottom came out to be 32 while length of bra of second brand came out to be 29. I stretched elastic of both bras to full during measurement. Plase solve my problem as i am unable to find a perfect bra size for me.

    1. I admit that measuring a bra band is something I have never done before or thought to do! Do neither fit you?

      Like I’ve mentioned in previous comments, unfortunately different brands can fit differently as there isn’t really an international standard. It’s just like how the same size across different brands for clothes can fit differently too. Different styles can also fit differently e.g. A strapless bra tends to have a tighter band compared to a T-shirt bra of the same size. This can be a headache, I know!

      My advice would be just to try bras in-store so you can find one that suits you, and if buying online, try sticking to a brand you are familiar with (although this may need some trial and error initially).

  22. My underbust is 27 inches, bust size is 34.5 inches.my right breast has length of 10.5inches and left breast has length of 9.5 inches. I have meadured length of my breast starting just from armpit till bottom of breast. 32B is not fitting me well.my breasts come out from top and sides while band size is perfect.should i go for 32C or 32D.

    1. Yes a 32B is definitely too small for you! I would probably start with a 32C as you have almost 3 inches between bust and band measurement. However, if you find you are still spilling over the cups, then go for a 32D. Don’t get too caught up in numbers- go by the fit of the bra. All the best!

  23. hi i got measured at a store they told me i was a 32a but the cup is too small and one place told me i was a 32b but with both cups when i raise my arms theres a gap in-between what size would i be?

    1. Sounds like you could be in between cup sizes. Try a few different brands in both 32A and 32B as different manufacturers can make their sizing a little different. You might be one size with one brand, and another with a different brand. Also give different styles of bras a shot to see if another type of bra fits your body shape better. All the best!

  24. hi ,
    my size is 32A bt i hardly get A cup. other thing is that my band size fits well bt cup seems to be kind of small. Like it bulges out . what should i do ?

    1. Hi, sorry I don’t quite understand your first sentence. Do you mean it’s hard to find A cups or you don’t fit in an A cup? If your breasts are spilling over the cups, I would suggest moving up a cup size to a 32B. If, on the other hand, the cups are gaping, then try a 32AA. I hope that helps.

  25. Hello, i wear a 34A ( it fits quite nicely) but i am trying to order a bra online and the only sizes that i can order are 34B, 32B, 30C, And 32A. Which one would fit me like the 34A? ( i might need a little bit more space on the cups… but it should be fine for now.)  Thanks for the help!

    1. Hi, if you feel like you could do with more cup space, try the 34B. If not, perhaps a 32B with a bra extender (same cup size as a 34A). Of course, ideally you should really be getting a bra in your own size- nothing is going to fit quite like it! But those are the options if you really want that particular bra 🙂

  26. i also forgot to mention the my under bust is 29 ( add 5 and its 34) and my over bust is 32…

  27. K so what do you recommend me to do the waist band of a 32A fits fine but the cup is to small and a 34A is to bug… Should I try a 32B???  And where can I get kne for cheap? Thanks

    1. Yes if the 32 band fits well, you should be trying a 32B, not a 34A. I can’t really help you with knowing where is cheap unfortunately. I am actually a pretty bad shopper! I think with bras though, it’s worth investing a wee bit in something good quality. I find that cheap bras e.g from cheap department stores tend to lose their shape quickly…then you end up having to replace them quicker too.

  28. We just found out my daughter is a 36AA would she be a 34A and have to use a bra extender? 

    1. Hi, yes that could work, although obviously it would be most ideal to try to look for a 36AA exactly. I understand that can be a difficult size to find though, so the 34A with a bra extender is indeed the next best option.

  29. Using your method of finding my bra size, I found that my under bust is 27 in (therefore 32) and my bust is 32. This would mean that I'd be a 32AA, correct? I can fit into a 32A in La Vie en Rose's bras, but I'm currently wearing a 32B from Victoria's Secret. I'm so confused as to what bra size I should be wearing. 🙁 

    1. Hi Jessie, how does that 32B fit? I think that your measured size should be a place for you to start, but you should always choose a bra based on how it fits since sizing can differ across brands (annoying I know, but it’s a reality). You might find that you need a different size for a different brand. If that 32B from Victoria’s Secret fits well, then you shouldn’t think too much about it 🙂

  30. So I'm 13 and I wear a 34a. It basically fits perfectly, I mean, the band was the most comfortable thing after trying from a 32 to a 36. The cup also fits relly fine and I feel like for the first time, it's a perfect bra for. (I wear a full coverage cupped 34a bra with under wire). The only thing I might ever complain for is that the top of my bra is a bit 'floppy', but I guess it's the style, because a 34a demi-bra doesn't have the same problem.
    The thing is, my mom is a 34b, or she claims to be it. I personally think she has much bigger boobs than mine and that she isn't just a size bigger. 
    My question (finally!) is: Since I shop for bras in the children's section (girls 7-14 or whatever) in department stores, are bras there the same as for adults bras? I mean, is a 34a in the kids' section the same as a 34a in women or in stores like Victoria Secrets?

    1. Hi Jennifer, I do imagine the sizing should be the same. I have never heard of it being different, although I have also never personally dealt with bras from the children’s section before so I’m sorry I can’t really say that with absolute certainty. Perhaps try doing a quick Google search to be sure? Your Mum could possibly be wearing the wrong size, but looks can also be deceiving and perhaps she looks bigger but really isn’t. I think you should definitely choose a bra on how it fits, rather than exact measurements, as there can be slight differences in how we measure ourselves and also differences in how different brands produce their bras. So if the 34 fits well and the 32 doesn’t, then yes you should definitely be wearing a 34 🙂

  31. [I'm still Jennifer who is 13 and wears a 34a bra  from above haha] I would also like to add that when I measure my band size, it's 27-28 inches, but the 32 band is too tight that I'm suffocating and end up with back pain. My bust is 33 inches. 
    & Yes I do wear my bras on the loosest hook.

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