How to find your correct bra size

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There's a common but completely wrong myth that your bra size can be found by your underbust measurement plus 5" (if that gives an odd number advice varies between 4" and 6"), with cup size given by subtracting the band size from your full bust measurement. For example, if your underbust measures 31", and full bust is 39", according to the advice above you would probably end up being recommended 36C. Buy a 36C bra with those measurements, and you will almost certainly end up with a band one or two sizes too big, and cup size anything up to 5 sizes too small! It is most important that you totally ignore this rubbish if you want a chance of finding a well fitting bra.

Band sizes:

The truth is that bra sizing is impossible to do reliably measurements alone, although a ballpark figure can be estimated. The above method will give you totally the wrong ballpark, except possibly if you have an unusually conical ribcage or are a man. Your actual band size is usually somewhere around your underbust measurement plus up to 4" in extreme cases, usually 0-2", sometimes even 1" lower.

There is some debate over whether the band size depends entirely on the underbust measurement, or the above breasts measurement needs to be taken into account as well. It may depend on the style of bra, some have a narrow band under the breasts, others (particularly for large cup sizes) have a much wider one so it's possible that it is a factor. One fairly relaible looking formula I've seen suggests taking the average between your above and below bust measurements, going for the small band size if you end up between sizes, maybe even subtracting an inch or two from the average if your underbust measurement is below 33". Some sites say you should just use the above bust measurement as your band size, but don't be surprised if the back band then rides up as it will fit above your breasts and not below, and in case your hadn't noticed your breasts are not on your neck!

This highlights another myth I've seen, that smaller sizes need to add more inches to the chest measurement than larger to get the band size. The reason for this is simple, it makes sure as many potential customers as possible believe their size is stocked by the shop! It has no correclation to actual sizes at all, anecdotal evidence suggests it's the other way around and that for small band sizes your band size is approximately equal to your chest measurement, and for large sizes only it's plus 3". Maybe in the realm of 50" chests the classic "add 5" becomes true.

So you have a bra you think fits well, how do you know if it's correct and if you need to change?

Pretty much the only sign of the band being too small is you physically cannot get into the bra. If it's uncomfortably tight it might be too small, or it may just be the alien (to most women!) sensation of wearing a bra which fits. Remember the first time you ever wore a bra? And then your first underwired bra? Did that feel so comfortable and normal you didn't notice it? If you've been wearing that size for more than a few days then it probably is too tight.

The easiest way of telling whether the band is too loose is to try on the next size down. If you can easily get into it, then you should have that size instead. More obvious signs are band riding up, being able to fasten it on the loosest hook even when new, chest pains, too much bounce and sometimes difficulty breathing. Some of these are not obviously traceble to a bad bra fit but magically go away when you wear the correct size. Underwires should lie flat against your chest, if there's a gap between the wires and your breastbone then that is a band size problem, not because you're wearing too small a cup size (although that can be a small factor, you'd need to be about 5 cup sizes out before that could be the only reason).

The correlation between band size and dress size is not what you'd expect. Band sizes below 32 are hard to find, so that must correlate to dreszs size 6/8, right? Wrong! It's more like size 10/12, maybe even 14 in some cases. If you are size 6/8 you should be looking at 28 band bras. It's really stupid that outerwear for those sizes is well catered for, but not bras, as women are not TARDISs with one size on the outside and a much bigger one on the inside!

Cup size

Generally, the cup size = full bust minus band size is not a million miles out. This of course depends on having the correct band size, but also depends on chest and breast shape, and how you're holding the tape measure. For UK sizes, the difference corresponds to cup size as follows:
<1" = AA
1" = A
2" = B
3" = C
4" = D
5" = DD
6" = E
7" = F
8" = FF
9" = G
10" = GG
11" = H
12" = HH
13" = J
14" = JJ
15" = K
copied from
American sizing conventions vary above DD cup.

It's amazing how body image and paranoia often totally override common sense. Many women wear the bra size they want to be or hope they are rather than what fits. Fear of very large cup sizes is very common, and a well fitting bra is especially important for large cup sizes. Often women who think they need breast reductions actually need a bra refit as their back pain comes from refusing to wear a bra which fits. Changing from a 38B to a 34F does not mean your breasts have got any bigger, it means they're now properly supported and you'll be much better off! One of the best things you can do when trying on bras is to realise how much the way your percieve yourself skews what bras you will consider trying, and think outside the box. If you're boobs are spilling out of a C cup but you cannot POSSIBLY be a D cup, then sorry, but you need a D cup or maybe even bigger. As far as I know there is not a bra size in existance which is supposed to have bulges, even pushup bras should give a smooth profile. If underwires are digging in this is also a cup size problem, they should not be poking anywhere near breast tissue.

The other way around seems to be less common. A few women wear a cup size or several too large, but it's pretty obvious that you're wearing the wrong bra size if cups are baggy.

Since you'll probably have to change band size to get the correct bra, bear in mind that cup sizes are (sort of) scaled to band sizes, when you go up a band size, the cup size labelled the same is actually one bigger. For example, 34D is the same cup size as 36C and 32DD. So if the cup is perfect but the band is too loose, if you were wearing 36C to start with you'll now need to look at 34D and 32DD to get the perfect fit.

Variation between brands and styles

Once you've found the perfect fit, not all bras will be the same. Even brands are not always internally consistent, you'll often find you need one band size for most bras and one up or down for others, and cup sizes can vary all over the place. Lepel's Athena and Miss Lepel ranges have such tight bands that the "add 5" rule actually works, as do some M&S Ceriso styles. However, these are the exceptions (and the only exceptions I've ever come across), not the rule, and using the band size it gives to estimate cup size will result in a poor fit so that rules still never works completely. e.g. if you normally wear 34D, you may find you need 36C in an Athena bra, but the bad formula might say 36B which is still wrong. Panache's Tango Plunge has such a loose band you'll need a size or two smaller than usual. Old Panache styles have rather generous cups, new ones seem to be very stingy. La Senza has very stingy cups. This is why tape measures alone will not work! But once you've found the right fit, you're unlikely to need much more than one band or cup size different.
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