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Bra University

13 Bra Tips You Need to Know

1. Bra size 101

The number: 28, 30, 32, 34, 36, 38, 40, 42, 44, 46 is the band size.
The letter: A, B, C, D, E, F, FF, G, GG, H, HH, J, JJ, K is the cup size.

2. Going down band sizes

There's an important rule that every woman needs to know when it comes to going down band sizes from your original size. 

For every band size you go down, you have to go up a cup size to compensate the difference.

Let's say you wear a 34B, the cup fits but the band is too big.

You measure a 30 band size.  A 30 band is two band sizes smaller than the 34 band.

This means you need to go up two cup sizes from the 34B to get the right cup size in the 30 band. So you would be a D cup in the 39 band size, so a 30D.

3. Going up band sizes

The same type of rule applies if you go up band sizes, but it's kind of different. 

If you go up a band size, you need to go down a cup size to compensate the difference.

Let's say you wear a 36DD and the band is too small but the cups fit. In order to go up to a 38 band size you need to go down a cup size.  You would want to try a D in the 38 band, or a 38D.  The 36DD and the 38D are the same cup size, the only difference is the 38 band is bigger around then the 36 band. 

4. Sister sizes

Did you know bras have sister sizes?  What this means is if you have a bra size that fits, but you want to adjust the band fit, you can find the sister size in a band size smaller or larger and get the correct cup size.  Remember, when you go up and down band sizes your cup size changes. 

For an example, a 32C and a 34B are the same cup size. The only difference is the band size. The 34 is a bigger band size than a 32.

Another example, a 34B and 36A are the same cup size.  The only difference is the band size.  The 36 is a bigger band size than the 34.

Here's an example of some other sister sizes.  So all of these cup sizes are the same.  The only difference is the band sizes.  

28DD
30D
32C
34B
36A
38AA
28F
30DD
32D
34C
36B
38A
28G
30F
32DD
34D
36C
38B
28H
30G
32G
34DD
36D
38C
28I
30H
32G
34F
36DD
38D

5. Cups and band too small

If your band and cup size are too small, you'll need to go up one band and cup size.

Let's say you wear a 34D and the cup and band feel too small. You'll want to try a 36D. This jump in band and cup size is one cup size and band size larger.

6. Cup sizes aren't stagnant 

Cup sizes aren't stagnant in band sizes.  This means a 34G and 36G aren't the same cup size.  The 36G is a cup size larger then the 34G because it's a band size larger.  

Another exmaple, let's say you have a 32DD and 38DD bra size.  Because the 38 band is three band sizes larger then the 32, the 38DD is going to be three cup sizes larger then the 32DD.  

7. How to fit lopsided breasts 

It's normal to have one breast that is larger than the other. What you do is you want to fit the larger breast because we don't want that one coming out of the top of the bra. If there's a significant difference between the two breasts, you can always use a thin molded cup insert in the smaller side to fill it out. We find if you have the right brand and bra style for your breast shape, you shouldn't have to do this.  

8. Red marks on skin is ok 

When you wear a new size and bra, I like to compare it to wearing a new pair of shoes.  Sometimes you need to break in your new bra and sometimes it can feel a little snug at the beginning.  It's completely normal to have red marks on your skin after wearing your newly fitted bra. Red marks is not a bad sign, unless the red marks are painful. Bras are made from elastic and are meant to be snug on your body in order to support your bosoms. Your bra will stretch with wear.  

9. How to put on your bra on

There's no wrong way to put on a bra. You can hook your bra behind your back with your hands. You can hook the back of the band in the front and twist it to the back and put your hands through the straps.  It doesn't matter, whatever is easiet for you.

10. Scoop those bosoms in

When you put your bra on, make sure to "scoop and swoop" your breasts into your bra. You'll find your breasts are coming out of the top of the bra.  Then take the top of the cups and lightly shake the breasts back into the bra. This makes sure the bra is in the correct position and your breast tissue is in the bra.

11. UK vs US cup sizing

Did you know there's a difference in US and UK cup sizing? To know if your bra is
US or UK sizing, check the tag on your bra to see if it says UK or US sizing.

As you can see not knowing there's a difference can make bra shopping hard and confusing.  On Bosom Besties, we let you know the US/UK size in every bra so there's no confusion.  We got your back and front ladies. 

US A B C D DD(E) DDD(F) DDDD(G) H
UK A B C D DD E F FF
US I J K L M N O
UK G GG H HH J JJ K

12. Space between breast and underwire

There should be a little bit of space between your breasts and your underwires from the front of your the underwire, to the back (by your armpit). You don't want the underwire to lay right against your breast tissue, you want it to at at the base or right below your breast tissue. This will help prevent chafing and underwire irritation on your breasts and make it more comfortable.

13. Some back fat is ok and normal

You're going to get less "back fat" when your band fits and is fitting snug and low in the back. When the band is laying low in the back, this is less fleshy than right under your armpit area. When your band is riding up the back, it pushes out this armpit area which makes "back fat" more prominent.  If you've had significant weight loss or have looser skin, you might have more of it.  So love your back fat, it's normal, it's healthy.  Remember every woman has it, not matter how thin she is.