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Bras: The Fit

Until recently, I never knew how a bra should fit or what constituted a good fitting bra. My method of choosing a bra had nothing to do with fit and everything to do with style. If any part of it had lace, ruffles, or picot trimming, if the colors were anywhere in the range of white, cream, pastel pink, and the fit was somewhat decent (i.e. I filled out the cups), I bought it. I didn’t pay attention to whether the straps fell off my shoulders or if the band hiked up in the back. I thought this was the normal quirks that are a part of wearing a bra. Not so, not so at all. Those letters A, B, C, D, DD/E, and DDD/F and those numbers 32, 36, and 38 actually mean something. Who knew? Once I discovered that bras should and can fit just as well as clothing, I did some research. The tips and information I write below are from various sources – Lucky magazine, Threads’ website, my own experience, etc. Regardless of where the information came from, it’s all good information. So, here is what I found out…

Band Size: To find your correct band size, use a measuring tape and measure your underbust (the fullest part of the rib cage just below the bust). When measuring underbust, make sure the measuring tape is level around the entire circumference of your body and that you are breathing normally. Any deep breaths in or out will distort the measurement. With underbust measurement, add 4” or 5” to get an even number. This is your correct band size.

Example: 28 (my underbust) + 4 (did not add 5 because it would give me an odd number) = 32 (my correct band size)

Cup Size: To find your correct cup size, use a measuring tape and measure around the fullest part of your bust, remembering to keep measuring tape level and to not take deep breaths. With this measurement, subtract band size. If the difference is 1, then your correct cup size is A. If the difference is 2, then your correct cup size is B. If the difference is 3, then your correct band size is C. And so on…

Example: 29 (my full bust measurement) – 28 (my underbust) = 1 (my cup size is therefore A ((although I can and do fit into an B. It depends on the brand)) )

In one of my readings about how to determine correct cup size, it wrote that cup size is found by placing a measuring tape on the sternum, between the bust, and extending it over the widest part of the bust to the point where it connects with the rib cage. If the measurement was roughly four inches, then your correct cup size is A. If the measurement was roughly five inches, then your correct cup size is B. If the measurement was roughly six inches, then your correct cup size is C. And so on… I do not agree with this method because it deals with width and not projection. Two woman can be the same cup size but one woman may be wider than the other and thus, her bust would be wider too. Cup size is about projection because essentially this is what the bust does, protrudes from the body. By subtracting bra band size from full bust measurement, you are calculating how much the bust is protruding.

Underwire: Any woman who is a B cup or larger should wear a bra with underwire. A good fitting underwire surrounds the bottom and sides of the cup and works with the bra’s band to provide shape and support and prevent sagging. Underwire doesn’t hurt, if it fits properly. If it is painful or bothersome, that means the wire is too close to the body and is digging into your skin . If this occurs, you should go up a cup size. If you are still totally against underwire, another choice is to look for brands, like Wacoal, that use a flexible boning instead of underwire.

Falling Straps: I know it sounds obvious, but first check if the straps are too loose. If they are, tighten the straps, making them taught but not causing the band to ride up in back. If the band starts to ride up, that means the straps have been tightened too much and instead, you need to go down a band size. The band is where most, if not all, of the bra’s support comes from. Consider it a shelf to store your books on. If the band, or the shelf, is riding up in the back, it is too loose and not doing its job. Go down a cup size if this is the case. Another culprit of falling straps is that the straps are set too far apart in the front and/or back. If this is the case, look for a bra with straps set closer together.

Gapping Cups: There should be no empty space between the bra’s cup and your bust. Your bust should fill out cups so that there is no spillage (you know what I’m talking about). If you’re guilty of gapping cups, go down a cup size; if your guilty of having a spillage, go up a cup size.

Strapless: Because strapless bras don’t have shoulder support, they need to fit tighter than a bra with shoulder straps to provide the same support. The easiest way to do this is to go down a cup size. Also, look for strapless bras with full bands and a large bridge between the cups. The wider band will help with support and the larger bridge will prevent your boobs from being smooshed together and looking like mono-boob.

Going up and going down: If you go up a band size, then go down a cup size (36C = 38B)

The size of the bridge: The bigger the bridge between cups, the less support provided.

There’s a lot of information on finding the right fitting bra. I simply shared what I thought was most important and relevant. If you have any other tips, knowledge, or information, feel free to share in the comments section.


  1. Reply


    So funny that you posted this. I for the first time had a bra fitting last week and boy was I off on my size. I was curious as to how they figured out my size and look at you sharing this wonderful post! 🙂 That Gilly Hicks bra is soo cute!

    • Reply


      Please do share how your fitting went. I have never had one and am curious as to what happens during the fit.

  2. Reply


    That is very useful information, thank you so much for posting this! I’ve ben the same size pretty much my whole adult life, apart from during pregnancies.
    Those are some truly beautiful bras pictured here too, btw (and thanks for your sweet comment on my skirt)

  3. Reply


    You are the second person to endorse Calvin Klein bras. Good thing tomorrow is payday … I recently bought a dress that is cut low enough in the back that the top of my bra shows once in a while. Tacky. I will shop for a new bra this weekend, but do you (or anyone) have any tricks for keeping the band out of site in the back?

  4. Reply


    I am always baffled by bra sizing! I think my measurements make me an outlier of the sizing calculations. If I follow the general formula, I would wear a 32B, which does not fit even slightly. Brittany from Thin and Curvy believes that the underbust measurement should be the band size, and then it’s subtracted from the full bust measurement in the same manner you described. That would make me a 28E/30D! Needless to say, bra sizing is not a simple thing to grasp (not to mention that every company fits differently), so I think trying different cuts/styles/sizes is pretty much the only way to find a well fitting bra.

    • Reply


      Totally agree. Like I said in the post, I “technically” am a 32A but depending on the brand and the style, I can and do wear a 32B. I use the information I wrote above as a guide when buy bras and making patterns. Plus, it’s always good to know why something is the way it is (a bra’s size)

  5. Reply


    What an interesting and informative article! Bras are not on the top of my list as favorite clothing to buy- maybe its because I’m buying the wrong size? Thanks for the tips!

  6. Reply

    Amy Royer

    I have needed some new bras for a while. Now I actually feel inspired to buy one.

  7. Reply


    It’s good to see an article about well fitting bras, having a good fit makes such a difference to the look of an outfit as well as to your own personal comfort. I am not sure however that I agree with the way you measure band size. For me personally that would give me a band size of 34 whereas in fact I am a 32. I usually buy my bras at Rigby and Peller in London who are renowned for getting a good fit by sight only (no tape measures!). Most people find that when they first go there they go down in band size but up in cup size.

  8. Reply

    Hannah Jean

    Hi there,
    I don’t want to be argumentative, but the +inches method of getting your band measurement is generally considered inaccurate/outdated. The bigger your cup size, the worse having that large of a band will be. My rib cage measures 33 inches, and I wear a band size of 32 or 34. Anything larger and the band hikes up in the back, which is a sure sign of poor fit.

    There are a lot of resources for getting a more accurate measurement. Try http://www.thinandcurvy.com/2010/10/how-to-measure-your-bra-size-correct.html

    I hope you find something that fits better! I would just hate for girls like me to measure their bands and add inches, then think their bras should fit like that, which is uncomfortable and unsupportive. I was in that rut for years. 🙁

    Good luck!
    -Hannah Jean

    • Reply


      I don’t consider you argumentative at all! The great thing about this hobby is that there are so many ways to do the same thing. For me, measuring my full bust and adding inches works but for you, it may not. Thanks for all the links so that others can read and choose which method works best for them!

  9. Reply

    Strange boobs

    I’m frustrated!!!! I need a 34 band, however a and b cups don’t fit the width of my breast. The 34 c usually fits the width, but my boobies don’t project into a c
    -36 slips horrible
    – a and b cup looks like a put on some miniature bra that won’t fit across my breast
    – and the 34 c has so much gap I could shove a box of Kleenex in there

    Help me please any brand suggestions for small rib cage, wide non- projecting breasts

    • Reply


      Strange boobs (I can’t believe I am referring to you with this name),

      I understand your frustration. I am small chested and have a VERY hard time finding a good fitting bra. I have three suggestions for this issue:

      1. Do you sew? If so, then buy the 34C bra and rub off / copy the pattern (do you know how to do this? If not, email me and I can show you how). Once the pattern has been copied, keep all pattern shapes the same excess for bra cups – reduce the excess fullness from the bra cup as shown here: http://www.madalynne.com/patternmaking-bra-cups

      2. I bought my favorite bra at H&M. I don’t know what country you live in but I highly suggest checking out their stores. They have such a wide range of bras and fits that I think you will be able to find something here.

      3. In the comment above, (Hannah Jane) gives links to blogs / websites that offer suggestions for smaller chested women as well as links to brands that accomodate us ‘non-projectile’ women.

      I hope this helps! Feel free to email me with more questions!

  10. Reply


    Hi, I was about to buy a bra online and I used to get 32a until I got fitted and they put me in a 32b in Victoria secrets. Should I get a 32a online at Gilly hicks or a 32b?

    • Reply


      Why not buy both sizes and return the one that doesn’t fit?

  11. Reply


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  12. Reply


    As was said by someone else, if you have a cup size larger than D it is very ill advised to add inches to your band size. As someone with G cups I cannot shop for bras in stores and have to buy online thus making accurate sizing essential. My underbust measures 33.75 and I wear a 34G/DDDD sometimes a 34H.

    For larger busted women reducing cup size to reduce the chest circumference is not an option. Go down a band size if it is really an issue. Also, when first buying a bra you should be on the loosest setting with the band almost too snug. With time it will stretch and you can use tighter and tighter settings.

    Also, large busted women beware of chain stores pushing their “sister” sizes, they will likely result in a poor fit and increased back pain.

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