How Big Is a 40C Bra?

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Do you find yourself wondering how big a 40C bra size is? Wearing a perfectly sized bra provides adequate support and is extremely comfortable. You’ve come to the right place if you’re unsure about your measurements and wondering if a size 40C will fit you.

How Big Is a 40C Bra? 

A bra size 40C corresponds to a torso measurement of 35 to 37 inches and a bust measurement of 41 to 43 inches. The sizes of your sister bras are 38D and 42B. A C cup has a bust that is 3 inches larger than your band measurements.

Graphic image of a woman wearing a blue tank top and black shorts that has a text explanation that a 40C bra size has a bust range of 42-43 inches and a band size of 39-40 inches

Sister sizes are different sizes for your current bra size. To find your sister size, go one band size up or down and one letter smaller or larger than your current cup size. The circumference of this bra size is large. However, the cup size is only slightly larger than average.

What Are the Best 40C Bra Types and Styles?

The following are some of the best bra types for 40C bra sizes:

Green push-up bra with underwire and adjustable straps placed on a black mannequin
  • Padded bra – this bra gives your breasts a little extra support, so they stay put under your clothes. The contour cups will slightly lift your busts for modesty.
  • T-Shirt bra this bra is suitable for use as everyday underwear. It makes you more comfortable and has a better shape without seams.
  • Push-up bra this kind of bra provides excellent side support, and the padding adds a natural look.
  • Cotton bra this soft cotton bra can be worn as loungewear or nightwear as everyday underwear. They are made of high-quality fabric and are soft against your skin.
  • Lace bra – this lovely bra will perfectly lift your boobs. Lift the bust to create a round shape if you prefer full coverage.
  • Seamed bra – this bra is typically made to give the wearer a smooth profile beneath clothing. They can also provide more support for heavier breasts.
  • Underwire bra this bra provides support to the full cup bra. This bra reduces bounce and gives your big boobs a round shape.

If you have a larger frame with average sized breasts, like a 40C, having a great, everyday bra is essential. My #1 recommended t-shirt bra is the Calvin Klein Perfectly Fit T-Shirt Bra. It was voted “Top T-Shirt Bra” by New York Magazine!

How Can I Tell if My Bra Fits Perfectly?

While selecting the best bra for your bust size, keep the following in mind:

  • The straps – the shoulder straps provide the remaining support. These straps are designed to help lift and even out your breasts. The straps should not dig into your shoulders. They should be snug enough to support your breasts.
  • The band should be snug and not too tight around your torso. You should be able to slip two fingers between your skin and your bra if the band is tight enough. The band should remain in place and not move when you raise your arms.
  • The cup – your breasts must fit inside your bra, regardless of cup size. The best cup for your breasts should have no side or top spillage. The cups should fit snugly, with no gaps or wrinkles in the fabric.
Tri-colored sports bra with underwire hangs on white hanger placed on pink background

Related Questions

When Should You Avoid Wearing Sister Sizes?

If you need assistance lifting a heavy bust, do not wear the sister size with a wider band. There is a chance that the band size will be too large and will not provide the necessary support. For this reason, it is more common to go down a sister size than up.

How Do I Know if I am a C Cup?

You can determine whether you are a C cup by measuring your breasts. You are a C cup if the fullest part of your breasts is 3 inches larger than your torso measurement.

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


The requirements of your breasts will always determine the best size to wear. The best bra size will provide support and stability to your breasts. You must also ensure that the cups properly fit your breasts, with no gaping or spilling out the sides.


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.