What Does ABCD Mean in Bra Size? A Complete Guide to Understanding Cup Letters

If you’ve ever stood in front of a lingerie shelf wondering whether you need a B, C or D cup, you’re not alone. Bra sizes can be surprisingly confusing, especially when the same letter seems to fit differently from one bra to another.

The good news is that bra sizing becomes much easier once you understand what the number and letter actually mean.

At Top Lady Lingerie, one of the most common questions we hear is: “What does the C in 34C actually mean?” So let’s make it simple.

What Do the Letters A, B, C and D Mean in Bra Sizes?

The letter in a bra size refers to the cup size.

It is based on the difference between your bust measurement and your underbust measurement.

Your:

• Underbust is the measurement around your ribcage, directly underneath your breasts.
• Bust is the measurement around the fullest part of your breasts.

The greater the difference between these two measurements, the larger the cup size generally becomes.

So, within the same sizing system, you will usually see cup sizes progress something like:

A → B → C → D → DD/E → F and beyond

But there is an important point that often gets missed:

A cup letter means very little on its own.

For example, 32D and 38D are not the same bra size.

The number matters just as much as the letter.

What Does the Number in a Bra Size Mean?

Let’s take 34C as an example.

34 = band size
C = cup size

The band is the part of the bra that goes around your ribcage. It provides much of the support, which is why getting the band right is so important.

A well-fitting band should feel firm and secure without being uncomfortable. It should sit fairly level around your body rather than riding up at the back.

If you find yourself constantly pulling your bra down at the back, the band may be too loose.

If it digs painfully into your ribs, it may be too tight.

What Does an A Cup Mean?

An A cup generally means there is a relatively small difference between your bust and underbust measurements.

However, being an A cup doesn’t tell us what your breasts look like or what shape they are.

You can have different breast shapes within the same bra size. Some women have more fullness at the bottom, some have more fullness at the top, and others have a more even distribution.

This is why bra style matters as well as size.

What Does a B Cup Mean?

A B cup generally represents a larger difference between the bust and underbust than an A cup.

But B doesn’t automatically mean “small breasts.”

The band size changes the overall proportions of the bra.

For instance, a smaller-band B cup won’t have the same cup volume as a larger-band B cup.

This is why it’s better to say 34B, rather than simply saying “I’m a B cup.”

What Does a C Cup Mean?

A C cup represents a greater difference between the bust and underbust than a B cup, within the same sizing system.

But contrary to a common misconception, C cup doesn’t automatically mean large breasts.

Your complete size is what matters.

A woman wearing a 32C will have different proportions from someone wearing a 38C, even though both have a C cup.

What Does a D Cup Mean?

A D cup generally indicates a greater difference between your bust and underbust than a C cup.

But a D cup isn’t necessarily “very large.”

A 32D, 34D and 38D have different proportions and cup volumes.

This is one reason we recommend looking at your complete bra size rather than choosing a bra simply because the cup letter looks familiar.

What About DD, E, F and Larger Cup Sizes?

Cup sizes don’t stop at D.

Depending on the sizing system and brand, you may come across:

A, B, C, D, DD, E, F, FF, G, GG, H and beyond.

The exact system can vary between countries and brands, particularly for larger cup sizes.

So if you’re buying a bra online, don’t assume that a size chart from one brand will automatically apply to another.

Always check the individual brand’s size guide.

How to Measure Your Bra Size at Home

If you’re ordering a bra online, taking accurate measurements is the best place to start.

You only need a soft measuring tape.

Step 1: Measure your underbust

Wrap the measuring tape around your ribcage, directly underneath your breasts.

Keep the tape level around your body and make sure it is snug without digging into your skin.

Write down the measurement.

Step 2: Measure your bust

Measure around the fullest part of your breasts.

The tape should sit comfortably rather than being pulled tightly.

Write down this measurement as well.

Step 3: Check the Top Lady Lingerie size guide

Use your measurements with the Top Lady Lingerie size guide to find your recommended size.

If you’re shopping online, we recommend taking your measurements before adding a bra to your cart rather than relying solely on the size you’ve worn in the past.

One small tip: avoid measuring over a heavily padded bra. A lightly lined or unpadded bra will give you a more useful measurement.

How Do You Know If Your Bra Fits?

Your measurements give you a starting point, but the real test is how the bra feels when you’re wearing it.

Here are some things to check.

The band stays in place

The back band shouldn’t ride up as you move around.

Your breasts sit comfortably inside the cups

There shouldn’t be significant spilling over the top, sides or centre.

The cups don’t gape excessively

If there’s a lot of empty space in the cups, you may need a different size or, sometimes, a different cup shape.

The straps feel comfortable

Your straps shouldn’t be so tight that they’re digging into your shoulders.

The bra feels supportive

You should feel held and supported without feeling squeezed.

A good bra should become part of your outfit—not something you’re constantly aware of throughout the day.

Why Can the Same Bra Size Fit Differently?

This is where bra shopping can get frustrating.

You might normally wear 34C, only to find that another 34C feels too tight, too loose or simply doesn’t sit properly.

That doesn’t necessarily mean your measurements are wrong.

Bras can fit differently because of:

• Cup shape
• Bra construction
• Padding
• Underwire shape
• Fabric stretch
• Coverage
• Brand sizing
• Your natural breast shape

A moulded everyday bra, for example, can fit quite differently from a lace bra or a push-up style—even when both have the same size printed on the label.

Size gets you close. Fit tells you whether it’s right.

What Are Sister Sizes?

You may also come across the term sister sizes when learning about bra fitting.

Sister sizes are sizes with a similar cup volume but a different band and cup combination.

For example, if your current band feels too loose but the cups fit well, you may be able to go down a band size and up a cup letter.

If the band feels too tight while the cups are suitable, you may be able to go up a band size and down a cup letter.

This can be useful when your usual size isn’t quite working, but sister sizing shouldn’t be used as a substitute for proper measurements.

Why Your Bra Size Can Change

Your bra size isn’t necessarily the same throughout your life.

Your body can change with:

• Weight fluctuations
• Pregnancy
• Breastfeeding
• Hormonal changes
• Age
• Changes in your lifestyle
• Natural changes in breast tissue

If your bras have suddenly started feeling uncomfortable, don’t automatically assume that the bra has become “bad.”

Your body may simply need a different size.

It’s worth taking your measurements again.

Nairobi? Come in for a Fitting

If you’re in Nairobi and would rather have someone help you with your fit, you can visit Top Lady Lingerie at Westfield Mall (Quickmart), 1st Floor, Shop B15, Gitanga Road, Lavington.

A professional fitting can be particularly helpful if you’re unsure about your band size, cup size or the style of bra that suits you.

Sometimes the issue isn’t simply choosing a bigger or smaller size. You may need a different cup shape, coverage or bra style.

Shopping From Outside Nairobi?

You can still find your size from home.

Take your underbust and bust measurements, then use the size guide provided on the Top Lady Lingerie website when choosing your bra.

If you’re between sizes or unsure about your measurements, it’s better to ask for help before ordering than to guess.

Top Lady Lingerie offers delivery across Kenya, so you can shop online wherever you are.

The Most Important Thing to Remember About Bra Sizes

Don’t get too attached to a particular letter.

You aren’t “supposed” to be an A, B, C or D.

The right bra size is simply the one that gives you the support, comfort and shape you need.

And if you find that you wear different sizes in different bra styles, that’s perfectly normal.

Your body hasn’t changed just because one bra fits differently from another.

Frequently Asked Questions About Bra Cup Sizes

Is a C cup bigger than a B cup?

Generally, yes, when comparing the same band size and sizing system. However, cup volume also changes with the band size.

Is a D cup considered a large breast size?

Not necessarily. The band size is an important part of the equation, so a D cup can represent different overall volumes depending on the band.

Why does my usual bra size sometimes not fit?

Different brands and bra styles can have different fits. Cup shape, padding, fabric, construction and your own breast shape can all affect how a bra feels.

Should I buy the same size in every bra?

Not necessarily. Your usual size is a useful starting point, but always consider the individual bra’s design and size chart.

How do I know my bra size when shopping online?

Take your bust and underbust measurements and compare them with the retailer’s size guide. At Top Lady Lingerie, use the size guide provided on the website before choosing your size.

Find a Bra That Fits You Properly

Understanding bra cup sizes, band sizes and measurements takes away much of the guesswork from lingerie shopping.

If you’re in Nairobi, come and see us for a fitting. If you’re shopping from elsewhere, take your measurements and use our online size guide to find your starting size.

And remember: the best-fitting bra isn’t necessarily the one with the size you’ve always worn. It’s the one that feels right on your body.

Shop bras and bra sets at Top Lady Lingerie and find something that fits your shape, your style and your everyday life.