I Cup Bra Size: How Big Could It Be?

The size of an I cup bra can vary from brand to brand, but generally speaking it is between a 36B and a 38A. Some styles may even offer sizes larger than that. An I cup bra provides ample support and coverage for women with bigger busts, typically providing two-way stretch fabric with reinforced sides for extra lift and support. They are typically lightly padded for a comfortable fit and come in a variety of colors, fabrics and styles. The I cup is great for women who don’t require the extra coverage or shaping that larger cups provide but have enough breast tissue to fill them out comfortably. 

natori bra

Bra Sizes Comparison 

To help you figure out your I cup bra size, we’ve provided this comparison chart for reference: 

Size Description Cups
Big Difference between the band and bust of 5 to 9 in. A, B, C, D, E, F, G, H
Large Difference between the band and bust of 10 to 12 in. I, J, K, L
Extra Large Difference between the band and bust of more than 12 in. M to ZZZ

What Makes Breasts Bigger?

Breast size is largely determined by hormonal changes in the body. Age, pregnancy, genetics and lifestyle factors such as diet and exercise can all affect breast size. Breast enlargement treatments such as implants, or hormone therapy [1] may also affect breast size. Additionally, wearing the right bra for your cup size can make a difference in how big or small your breasts.

28f bra

What Are the Benefits of Having Larger Breasts?

Having larger breasts can provide many benefits. Women with larger breasts often feel more attractive and confident, as they tend to draw attention to their curves. Additionally, having a larger cup size tends to provide greater support and coverage than smaller cups do. Larger breasts also may be seen as being more comfortable when wearing certain types of clothing, particularly blouses and dresses. Finally, having larger breasts can often help with back pain, as wearing a bra that is properly fitted for the breasts’ size helps to keep them in place and distribute their weight more evenly across the back. 


An I cup bra size is slightly smaller than a D cup and provides ample coverage and support for women with bigger busts. The right bra size, combined with lifestyle factors such as diet and exercise, can have a big impact on breast size. Women with larger breasts often feel more attractive and confident, while enjoying the additional support and coverage that larger bras provide. 

No matter what size you are, it’s important to find a bra that offers the right fit and support for your body. 

For more information on finding the right size for you, check out our Bra Sizing Guide! We’re here to help you find the perfect fit. 

Good luck on your journey to finding the perfect I cup size bra!  We wish you comfort, confidence and support in your new bra.  Happy shopping!

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