Find Your Fit


Small Cup Bra Sizing Guide for Petites

There are two fairly reliable ways to find your bra size if you are small-busted. Try each of these and bring your results with you to try on bras in each size you came up with; you may find that one of these is consistently a better fit than the other, or you may need the first size in one brand and the second in another. The calculation for each strategy is the same, but one uses your overbust measurement while the other takes your underbust.

How to Measure

There are 3 measurements you will need in order to find your size. Do not stretch the tape measure, but try to get it as flat as possible against your skin all the way around. Record each of the following, rounding up to the nearest half-inch:

  1. Overbust [O]– Measure across the top of your chest just below your shoulders in front, under your arms and straight across your back at the same height.
  2. Fullest Bust [F]– Measure your breasts at their fullest area (usually at or just below the nipple) with the tape straight across in front and around your back at the same height. Between the fullest points of your breasts in front, the tape should not touch your body.
  3. Underbust [U]– Measure beneath your breasts and around under the shoulder blades in back, where the band of your bra goes.

Now you should have three numbers, each ending in .0 (whole number) or .5. Next I’ll show you how to use them.

Calculate Your Bra Size

Choose either the overbust [O] or the underbust [U] measurement for the following calculations to get your band and cup size. Then, try the same calculations with the other measurement.

  • Band size = chosen measurement [O] or [U] rounded to the nearest whole even number.
  • If the measurement is odd, i.e. 31 or 31.5, round up; if it is even, i.e. 30.5 or 32, round down for half-inch measurement or take the even whole number as your band size.

  • Cup size in inches [C] = fullest bust measurement [F] minus original chosen measurement [O] or [U].

Cup Size Chart

    If [C] equals… then your cup size is:

  • 0 – .5 in: AA
  • 1 – 1.5 in: A
  • 2 – 2.5 in: B
  • 3 – 3.5 in: C

  18 Responses to “Find Your Fit”

  1. I am 32AA. Cant find a bra that is wireless that is
    my size.

  2. I took the test and got different measurements based on whether I used U or O.

    See below:

    F: 33.5
    U:31 (rounded to 32)

    F (33.5) minus O (34) = -.5


    F(33.5) minus U (32) = 1.5

    So I am not sure which is right. Your help would be much appreciated! Thanks!

    • Hi Ashley, here are the sizes I suggest you try: 32A, 34AA, and 32B. You might also find that there are some 34A bras that fit you, but make sure these are tight enough in the band so as not to ride up when you lift your arms.

  3. O- 29

    Which size do you think would be best? I now I’m a 32 band size because that size is the most comfortable but what cup size xx

  4. I got different measurements as well:
    U: 25in (rounded to 26in)
    F: 30in
    so that would put me at 26D ?

    O: 28in
    F: 30in
    = 28B

    I have VS Pink push up bra in 30A and 32AA, the cups are too small in both and 32 band is riding up my back. I got VS Pink multi way push up bra in 30B the cups fit great but the bra is really uncomfortable :/ I am planning on ordering Aerie Hannah in 30B but i wonder if it gonna fit me and if it runs similar to VS pink line…. :/

    • Hi Asia. It’s no surprise that your size 32 is riding up! I’d have you try a 28C, with 30B as an alternative if it’s too hard to find size 28. The VS Pink push-up bras do fit similar to Aerie Hannah, except Hannah is way more comfy.

  5. I never know what size to get because It is difficult to find straps that fit me but my measurements are
    F:29-30 depending on my cycle
    what size should I be?

    • Hi Clara,

      Your measurements make you a little bit harder to fit, first of all since you are so petite and second because your overbust is larger than your fullest bust. I’d say come see me and get fitted in person, but of course most people reading this are not able to do that! Try a 30A or 28B to start with.


  6. Hi Amanda,
    I have some problems with these measurement:
    O – 30
    F – 30.5
    U – 27.5
    which size do you think suit me best? now I’m wearing 32A because it’s almost impossible to find some bra below 32 in town where I live. However I notice sometime there’s a gap between my bra and my flesh and I dont know it happened because I wore wrong size or because of the push up. Thank you so much.

  7. Could you help me?

    I seem to have a job figuring this out.

    My measurements are


    I currently wear 34AA. I feel this is probably correct because I am very small and flat looking although I don’t fill out the cups completely like it does not fit snug against the top of my bust when standing straight and just loose so when I bend over as well it just has no support there and people can get an eye full. I have brought this size bra from more than one shop and they are all the same with regards to the fitting. I am sure I am not a AAA?? I occasionally wear a 32A because trying to find bras in 34AA is difficult where I live. The 32 band does seem better than a 34 but I gape in the cup still but I do like that it is tighter so I feel a smaller band than 34 is probably right for me maybe? I would just love a bra that actually fits snug against my breasts and not gap all the time.

    Any suggestions would be appreciated. Thanks

    • Sorry I meant my measurements are O-31 (I put 32 before by accident) F-31 U-30 (Although I would say more 29 for under but I rounded it to 30)

      Could you help me determine the best sized bra for me based on those measurements? Thanks

      • Hi, based on everything you’ve said I would recommend a size 32A. Other sizes that might work: 30A, 30B, 32AA. Finding a 32A bra that doesn’t gap in the cups can often be a matter of trying different brands and styles; you may have been wearing bras cut with too much coverage, or the angle of the cup may have been wrong for your shape. Try a petite brand like The Little Bra Company or Wacoal Petites, as these are less likely to gap. The Little Bra Company tends to run tight in the band, so you may need a 34 band in these, but I would have you try a 32A to start with.

  8. oops i made a mistake – my fullest is more lik 28 or 28.5 inches (not when rounded).

  9. Also a lot of 32a are too big in the cups.

  10. Hi Heather,

    You might want to try a 32AA, or a 30A if your underbust measures 29 or less.

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