How to Measure Your Bra Size

Believe it or not, 95% of women-at least-wear an incorrectly sized bra! They're wearing one too large in the back and too small in the cups (the opposite is impossible, you can't breathe in a bra that's too small in the back-literally). And although the average bra size is often quoted as being 36C, this is just the most popular size that women buy. Most people who wear an "average" 36C bra should actually be wearing somewhere around a 30E.

So how do bra sizes work? Most people know that bra sizes are made up of two parts - a number and a letter. The number is known as the band size or back size and the letter is the cup size. However, what many people do not realise is that cup sizes are in proportion to the band size, so a D cup, for example, is not the same size in every bra. A 32D is the same size as a 34C or 36B, but on a smaller frame. A 28F is actually five cup sizes smaller than a 38F, so it is not as big as it sounds! If you are fairly slim, then you may well need a large cup size even though your bust does not look any bigger than average.

Larger women may still need a small band size because this relates to the size of your ribcage only - you can still be curvy everywhere else! And losing or gaining just a few pounds is likely to have an effect on your bra size but it is not often considered even when other clothing is resized. And then there are the times when you go for so long wearing a certain size that you don't even realise it does not fit well anymore and you stop noticing the discomfort and treating it as normal! If you are looking for a better fit, here is how to find your true bra size.

Measure your band size

Run a tape measure all the way around your body just underneath your breasts and take a measurement in inches. Make sure the tape measure is horizontal and fairly snug. Your arms should be down.

If this measurement is an odd number, then you should try out bras in both the size below your measurement and the size above. For example, if you measured 31 inches (78.7cm), your band size could be 30 or 32. In 9 out of 10 cases, it is 30. If you are EVER unsure, lean towards being too small in the back and too large in the cups-a too-small band can be worn with a bra extender in the back, but a too-large band is completely unusable and gives no shape.

If your measurement is already an even number, this is almost always your band size. The exception is if you are extremely underweight and pretty much all bone (in which case you will want to go up a couple of sizes) or overweight and mostly fat (in which case you will want to go down a few).

Determine your cup size

Since everyone's breasts are different in terms of shape (even between your own breasts), the most accurate way to determine your cup size is by using your current bra size as a starting point. The cups are sized relative to the band, so if you were to try a smaller band size but keep the same cup size, the cups would be too small.

For every band size you have dropped, you will need to increase the cups by one size. For example, if you are currently wearing a 34D bra, and you measure 28 inches, you should probably wear a 28F.

Cup sizes are as follows: AA, A, B, C, D, DD, E, F, FF, G, GG, H, HH, J, JJ, K, KK, L, LL. Do NOT buy bras from a website with any other cup sizing method! (The exception being if they don't have L or LL cups, which are still fairly uncommon.)

Try on a bra with the band and cup size you have arrived at in these steps

You should not regard this as your definitive size until you have tried on a few bras, and even then you will often find you need a different size in different brands or styles of bra.

After taking the bra off its hanger the shoulder straps will need to be lengthened. Put your arms through them and lean forward slightly so that your bust falls into the cups.

Fasten the bra on the largest set of hooks and eyes. Don't worry if it is tricky to fasten, if you are trying a smaller back size you will notice that you need to stretch it around you to make the hooks and eyes meet.

Still leaning forward, take hold of the underwires and give them a wiggle from side to side to make sure you are settled comfortably into the cups.

For each side in turn, slip your hand into the side of the cup and lift each breast towards the centre.

You will probably have to adjust the length of the shoulder straps. Slip them off your shoulders and adjust the sliders so that the straps are short enough to stay in place but don't cut in.

Check the band size

The correct band size is the smallest you can comfortably wear. (Yes, this might be smaller than your underbust measurement-bra bands are quite stretchy, especially at 42+.) It needs to be firm enough that the bra is still fairly supportive without weighing down heavily on the shoulder straps.

You should be able to run your fingers around the inside of the band, but not much more. A good rule of thumb is that you should be able to fit no more than a fist under the back of the bra.

It should fit on the biggest adjustment, but will probably be too tight if you try to fasten it on the smallest size. Bras are designed to fit like this so that you can tighten the band as the elastic starts to wear out.

>If the band is roomy enough for you to be able to comfortably fasten it on the tightest adjustment, try a smaller band, for example if a 32D is too loose, try a 30DD. Remember that the cup size has to be changed when you move to a different band size - for every band you go down, you must go up by one cup size in order for the cups to remain the same capacity and vice versa.

If you are suffocating to death in your bra and you HONESTLY can not breathe (e.g. if you are an asthmatic who is suffering an asthma attack), you should try a band up and a cup down, e.g. 26J (yes, that is a real size, and more common than you would think!) to 28HH.

Check the cup size

Check the cup size.The correct cup size should be completely filled out with no wrinkling of the fabric or space in the cups, but any spillage means the cup size is too small, even in low cut or pushup bras.

Check around the cups for any bulging, not only at the front but also at the sides under your arms (and your back!).

Make sure the underwire encloses your whole breast and lies flat against your rib cage.

Check at the sides under your arms to make sure the underwires are sitting on your ribs, not on soft breast tissue. If they are cutting into the sides of your breasts then you need a larger cup size.

If the underwires are pressing painfully against your breastbone at the centre front you may need a smaller cup size or you could try a plunge style with a lower centre front (this is more likely to be a cup size issue than a band size issue.)

If you think the cups might be too small but you are not sure, try on a bigger cup size as well to double check. It will usually be obvious if the smaller size fits better.

See how it looks with your top on.

You have found a new bra that fits well, maybe in a different size or style to the ones you aree used to. Now it is time to see what it does for your figure! If you are trying a t-shirt bra it is also important to make sure it gives you a smooth line under fitted clothes.

If you look side on to the mirror, you should be able to see that your bust is approximately halfway between your elbow and your shoulder.

In a well fitting bra, your bustline will be supported at the right level. A lot of people find that their clothes fit a lot better, and they discover a waist that could never be seen before! If your bustline had previously been quite low because of a poorly supporting bra, you may even find that you need to wear a smaller dress size.

A fitted t-shirt will show up any bulges from cups which are too small, and likewise a moulded bra that is not filled out will show lines at the bust where the edge of the cups are visible. It is also useful to make sure that the colour of your bra is not showing through a thin or light coloured top - if you need to make your bra invisible, go for seamless cups which match your own skin colour rather than the colour of your top.

It is a common concern that wearing a smaller band size will make a big bulge around your back. However, these bulges are actually caused by the back of the bra riding up when it is too large. You should find that when the band sits lower at the back, it fits firmly and remains horizontal, rather than pushing upwards creating a bulge.


Cup sizes above D tend to vary significantly between manufacturers. However, if it does not go according to the guide given above, you should not buy from them - they will generally have very little idea about proper fit.

A well-fitted bra should provide 90 percent of the support from the band, not the straps.

If you have uneven cup sizes, go with the bigger side. You can support the smaller breast by making that shoulder strap slightly

If you want your bras to last and keep their fit, never wear the same bra two days in a row, even if it has been washed. You should have at least three bras which you can wash and wear in rotation, allowing the elastic to fully recover before it is put under stress again.

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