Bra Sizes Explained: How Bra Sizing Works

Fit Tips by Sugar Candy - February 5, 2020
basic bralette cocoa beige

“I’m a D cup”, “She was as big as a handful”, “My sister is a G cup”. We’ve all heard phrases like these, but in the wise words of Einstein, it’s all relative.

For example, someone that has G cup breasts and a 32 band is going to look completely different from someone with a G cup and a 38 band. So, what’s the science behind all of this mumbo jumbo?

How do bra sizes work:

There is a measurement for the underband and a measurement for the cup, and your bra size comes from the relationship between the two.

Let’s break it down:

Say you are a ‘36E’.

The prefix ‘36’ refers to the underband measurement – under your bust, around the ribcage. So you would be measuring 34-36 inches.

The letter refers to the difference between your overbust measurement and your underbust measurement, in inches. So if your overbust measurement is 41 inches, that’s 5 inches more than your 36 inch underbust. E is the 5th letter in the alphabet, therefore you’re an E cup. Is your mind blown yet?

Easy right?

But wait, there’s more…

If you find the perfect bra but it’s not in your size, you may be able to purchase the same one and get a similar fit if you use the following rule of thumb—go up one band size and down one cup size, or the other way around. This is called Sister Sizing.

Sister sizing explained:

Basically, the capacity (actual breast size) of a 32C is the same as a 34B. The capacity of a 32B is the same as a 34A. Get the correlation? You can go backwards too – a 36C has the same capacity in the cup as a 34D, and so on…

Go up a band size and down a cup size, or go down a band size and up a cup size.

Check out the chart below to see what we’re talking about!

full bust bra size chart

To make it really simple—see the chart below (just for fun):

fruit grid

So if you are a C cup, you could actually be the same size as an A cup, it all depends what your underbust size is. Confusing right?!

Bra support explained:

Bras are usually designed according to the amount of support required for the size they are supporting. If you have a smaller bust to support and are more petite in the frame; you can get away with narrow straps, thinner elastics and a single hook and eye at the back.

If you have a larger bust to support, wider straps, stronger wires and generally more construction is required to do the work to keep those puppies up. You’re welcome.

It can be a bit disappointing when you see the B cup model online and the bra that you’re buying arrives looking completely different in your size. Never fear, because it’s all done for the ultimate job of supporting your pups.

How to find your bra size:

Please note, this is a general rule of thumb and requires a tape measure, a non-padded, well fitting bra and potentially a mirror.

1. Head to the SugarCandy website for our easy to use fit calculator (click Fit Me* menu) that works out what size you are in SugarCandy.

2. Measure your underbust with the tape measure parallel to the floor. If you’re unsure, use a mirror or a good friend (bad friends won’t work).

3. Enter your findings on our calculator.

4. Then measure your overbust, this is across the fullest part of your bust and should also be parallel to the floor. Hold this firm but be careful not to pull it too tight so that it dints your bust.

5. Enter your findings to the calculator and voila!

There’s your size.

This is based on a nifty algorithm that works out the correlation between your underbust and overbust to figure out your size. Clever, yes?

However… Please remember that the tape measure is not the best way to work out your size if you have a fuller bust as, just like the scales, the tape measure can also tell lies.

Finding the best fit:

Ok, so you’re in the fitting room and you think the bra you’re wearing fits, or is pretty close to fitting. Here’s a list of some things to check along the way:

1. Underband first—let’s go! It’s best to fit on the middle hook, by the way.

  • Is the bra riding up your back? If yes, go down a band size.
  • Does the bra feel too tight around the body? If yes, go up a band size. A little hint here is whether you can breathe or not.

2. Now the cups. The wires need to be nowhere near your breast tissue at all.

  • Are the wires on your breast? If yes, go up a size.
  • Is the top cup digging in? If yes, go up a size.
  • Is the top cup wrinkling? If yes, you may just need to adjust your straps.
  • Do you feel like your bust is supported (aka nipples facing forward)? If it’s a no, you may need to change the style of bra to something more structured and supportive, or simply adjust your straps.

If you follow these simple steps each time you try on a bra, you’ll be sure to find the perfect fit each time.

Not all styles of bra suit every bust and body *shock horror*. Just like not one style of jean will be great for everybody.

Work out what works for you and what type of clothing you like to wear, and the rest will fall into place (slight pun there).

  • If you like to wear white t-shirts, then a nude t-shirt bra would be great.
  • If you like to wear plunging, scoop neck tops, then a plunge bra with a low front could work.
  • If you have sloping shoulders, try a bra that is more triangular in shape.
  • If you are wider set, try a balconette bra.

Final take:

Whatever your bra size, breast shape or body type, remember that you are unique and there will be something out there for everyone.

There are lots of different bra brands out there, and they all have their own different ways of sizing. Within each of these brands, their sizing can also vary between different styles and seasons. You also can vary in size between different styles, seasons, or even day to day.

For the best outcome, always try it on first. If in doubt—buy a seamless bra that covers a range of sizes, such as Sugar Candy bra *hint hint*.

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