C Cup vs B Cup Bra Sizes In Review

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People have assumed that C and B cup size bras were the standard cup size in the US, ever since cup sizes were invented. This belief can make it difficult for people to differentiate between the C cup and the B cup. In this post, I’ll discuss these two sizes and their differences in depth.  

C Cup vs B Cup General Overview 

The first bra sizes were small, medium, and large which soon evolved to sizes A-C. The underwear department has experienced many changes since cup-size bras first entered the market.

Graphic image that features a drawing of two figures wearing a red bra, which compares a C cup bra size against a B cup bra size

C Cup Size

Socially and culturally, C cup breasts are considered to be an average sized bust. In reality they are a little smaller than the average bra size.

A C Cup bra size is defined as the bust size measuring 3 inches larger than the band size. For example, if you have a 37 inch bust size (measured across your bust) and a 34 inch band (measured across your chest, right below your breasts), then you would be a 34C.

B Cup Size

Across the board, B cup breasts are considered to be on the smaller side. This is the second smallest size readily available on the market after the A cup size.

A B Cup bra size is defined as when the bust size measures 2 inches larger than the band size. For example, if you have a 34 inch bust size (measured across your bust) and a 32 inch band (measured across your chest, right below your breasts), then you would be a 32B.

C Cup vs B Cup Similarities and Differences

Before looking at the similarities, differences, and major distinguishing factors of the two sizes; let’s look at what makes one have either a C cup or B cup size. A-C cup or B cup breast size may vary depending on:

A red laced bra in a mannequin
  • Genetics: If a mother has small breasts, the girl is likely to have the same and vice versa. Breast size can be hereditary.
  • Weight: Fat and weight is important in terms of density and breast tissue which affects the cup size you wear.
  • Exercise: The pectoral muscles a woman builds during exercise increases the amount of breast tissue. This hardly affects your breast size but it can make them look perkier.
  • Breastfeeding and pregnancy: A hormonal change in pregnant women causes them to have more collagen fibers that help give their mammary glands volume, which increases their breast size.

Comparing C Cup and B Cup Bra Sizes

Cup Size Bust/Band Difference Average Weight Best Bra Styles
B Cup 2 inches1.72 poundsWireless, push-up, bralette
C Cup 3 inches2.26 poundsWired, plunge, t-shirt


C cup size and  B cup size are considered to be the average size for most women.  This is because they fall in the middle of the range from A -G.

A close-up image of a white laced bra


Bra cup sizes are determined more from the shape of a woman’s breasts rather than their actual size. The distinct features that differentiate the C cup from the B cup are:


If I are using a fruit analogy, the C cup resembles a grapefruit and the B cup is an orange. C and B cups look different from one person to another depending on both your ribcage and bust measurement. The B cup size is slightly bigger than the smallest size, the A cup.

It is important for every woman to accurately measure their cup size using a tape measure at home or get assistance with measuring their size in a bra or lingerie store. No matter your breast size, they need to be supported with a well fitted bra.

Bust sizes

Considering that most brands range from A (Smallest) to the letter F (Largest), the C cup is considered average. A C cup bust measures three inches larger than the underbust circumference. The B cup bust measures two inches in larger than the band measurement. The cup volume will differ based on the bra‘s unique size.

Breast size can fluctuate for several reasons, most of them having to do with hormonal changes due to a woman’s menstrual cycle. Your breasts could either move up one size bigger or go down a size depending on what part of your cycle you are in.


Cup sizes may differ depending on how much breast tissue a woman has. The average B cup size breasts weighs approximately 1.72 pounds. The C cup size bust weighs roughly 2.26 pounds.

Breast Augmentation

Breast augmentation in simple terms can be defined as a form of breast enhancement. It can also be called augmentation mammoplasty. The procedure entails putting implants below the breast tissue.

The question of whether a C or B cupped size should undergo a breast augmentation depends on a doctor’s guidance. Generally speaking, you should never go for more than two size cup differences. A-C cup would be ideal for women who have a natural A or B cup.

Breast implants require adequate support from your bras, and you’ll need to update your wardrobe with the correct size.

Major Distinguishing Factor 

The major difference between a C and B cup is the amount of space the breasts occupy in terms of inches. A C-sized bra puts your breasts at 3 inches larger in circumference than your rib cage.

A person holding a black bra

With a B-sized cup, there is a 2 inches difference between your ribcage and bust measurement.

When to Use a C Cup Size Bra

You can use a C cup size bra when wearing the following bra types: 

  • Wireless Bra: This style of bra is supportive even though it’s wireless. It rests flat and smooth against the body, so it’s perfect for fitted clothing.
  • Push Up Bra: This style of bra has a sexy design, as it pushes your breasts up and forms more cleavage. These are also usually well padded, so they can add more volume to your bust.
  • Seamless Bra: This style of bra provides comfort thanks to the lightweight, breathable and flexible fabric.
  • Seamless Underwire Bra: This style of bra is great for wearing almost any type of top as it won’t give you visible bra lines and provides full coverage. It has strong support with comfortable padding that enhances your bust.

When to Use a B Cup Size Bra

A B cup bra is a great choice when wearing a:

  • Wire free bra: This is a good bra to wear if you stretch and move a lot. It has removable pads so you can wear them under your day-to-day outfits.
  • Lace bra: While this style of bra does have an underwire, it’s comfortable and super sexy.

Related Questions

Are B and C Cups Good Sizes?

Like all sizes, B and C cups are good sizes. There are no “bad” sizes. While B and C cups are generally considered smaller, keep in mind that breast volume varies per person. You can highlight or increase the appearance of your bust with the right bra.

What Does a B Cup Look Like?

A B cup is quite small in comparison to other sizes, with an overbust circumference of just two inches. Celebrities with B cups include Jessica Alba, Rihanna, and Miranda Kerr.

What Does a C Cup Look Like?

In comparison to other cups, the C cup appears smaller as well. Celebrities with C cups include Salma Hayek, Emily Ratajkowski, and Cara Delevingne.

Bra Size Measurement & Cup Size | A, B, C, D, DD Bra Sizes AND Extra Large Breasts


B cup-sized women and C cup-sized women are beautiful. In fact, all bra sizes are! As long as you pick the best bras to flatter your silhouette, your boobs will look fantastic no matter their size.


Allena is the Founder and Editor of The Better Fit, a platform dedicated to empowering women with practical advice on bras and fitness, inspired by her own revelation of the widespread issue of incorrect bra sizing. Her expertise and tips have been recognized by major publications such as Cosmopolitan, Better Homes & Gardens, Insider, and NBC, making her a trusted voice in women's wellness and lifestyle.