What Do Bra Sizes Mean? A Guide to Finding Bras That Fit

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Figure out your bra size and learn when to size up or down

Co-authored by Elle Monus and Elaine Heredia, BA

Last Updated: March 4, 2026 Fact Checked

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• Number & Letter Meaning
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• Finding Your Size
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• Size Ranges
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• Fit Considerations
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• Video

|Show more |Show less

Many women of all ages wear bras, and tons of brands sell them. So why is it so hard to find one that fits just right? When you understand how bra sizing works, you'll have much more confidence and might even enjoy shopping for bras again! Read on as we explain bra size numbers and letters and how to find your size, cover the wide range of bra sizes, and offer tips on fit considerations from image consultants and stylists.

What do bra sizes mean?

The number in bra sizes refers to the bra's band size, which is a measurement of the circumference of your torso just below your breasts. The letter in bra sizes refers to the size of the bra cups. The bigger the cup size, the more breast tissue it's designed to hold.

Steps

Section 1 of 4:

Bra Size Number & Letter Meaning

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1. 
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   The number refers to the bra's band size in inches. Band size is a measurement of your underbust, the area at the top of your ribcage just below your breasts. This is also where your bra band typically sits!

   Meet the wikiHow Experts

   Elle Monus is an image consultant with over 11 years of experience. She specializes in holistic approaches to branding, size-inclusive image counseling, and personal styling.

   Katie Quinn is a personal wardrobe stylist and an image consultant. With over 11 years of experience, she specializes in helping men and women understand their goals and improve their wardrobe.

   Jordan Stolch is an image consultant and style advisor with over 10 years of experience. She specializes in helping people use clothing to a strategic advantage.
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   The letter refers to the bra's cup size. The bigger the cup size, the more breast tissue the bra is designed to hold. In US bra sizing, cup sizes start at the beginning of the alphabet with AA and go all the way to J (in UK bra sizing, it's AA-GG).
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Section 2 of 4:

Finding Your Bra Size

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1. 
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   Measure your band size in inches. Wrap a fabric tape measure snugly around your torso, right below your breasts. Don't pull it so tight that it feels constricting, but don't leave it so loose that it slips down. Write the number in inches, and you have your band size!
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   Measure your bust in inches. Bend over slightly and wrap the measuring tape around the fullest part of your chest, across your nipples. Pull the tape snug, but not so tight that it hurts or pushes your nipples up into your breast tissue. Write down the number in inches.
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   Subtract the band size from your bust measurement to get your cup size. The difference between the sizes corresponds to a letter, which is your cup size. Here’s a chart showing different bra cup sizes:

   • Less than 1 inch (2.5 cm) = AA
   • 1 inch (2.5 cm) = A
   • 2 inches (5 cm) = B
   • 3 inches (7.5 cm) = C
   • 4 inches (10 cm) = D
   • 5 inches (12.5 cm) = DD
   • 6 inches (15 cm) = DDD (E in UK sizing)
   • 7 inches (18 cm) = DDDD/F (F in UK sizing)
   • 8 inches (20.5 cm) = G/H (FF in UK sizing)
   • 9 inches (23 cm) = I/J (G in UK sizing)
   • 10 inches (25.5 cm) = J (GG in UK sizing)
   • Combine the band size and cup letter to find your bra size!
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Section 3 of 4:

Bra Size Ranges

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   Bra band sizes typically range from 28 inches to 46 inches. Some plus-size brands, like Cacique by Lane Bryant, sell bras with bands up to 54 inches around. Bra sizes come in even numbers only, so if your band size is an odd number, try on the size above and below to see which one fits better.
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   Cup sizes range from AA-J in US sizing. Another important thing to know about cup size is that it decreases by one full cup for every increase in band size. Use the phrases "up in the band, down in the cup" and "down in the band, up in the cup" to remember how to find the right bra size.

   • For example, if a 34C bra is too small in the band, but just right in the bust area, you might need to size up to 36 for the band size and down to a B cup to keep the same cup size for your breasts. If a 34C bra is too big in the band, size down to 32 for the band size and up to a D cup.
   • Bras with the same cup size but different band sizes are called "sister sizes." In the example above, 34C and 36B are sister sizes, as are 34C and 32D.
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Section 4 of 4:

Fit Considerations When Picking a Bra Size

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   Increase the cup size if you see spillage and decrease it if you see gaps. Image consultant Elle Monus says you can tell if a bra is ill-fitting based on how the cup fits around your breasts. If there's a gap between your flesh and the cup, it's too big. If your flesh spills over or around the cup, the bra is too small.
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   Decrease the band size if your bra rides up in the back or the straps are falling. Personal wardrobe stylist Katie Quinn says that when your bra rides up in the back or your straps are always falling, no matter how much you tighten them, these are signs you need to size down the band. She advises keeping the same cup size or going up one size to get a more comfortable fit.
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   Ensure you can wear your bra on the loosest hook comfortably. The loosest hook is the one closest to the end of the band. If you have to wear your bra on the tightest hook (the one furthest from the end of the band) to be comfortable, you may need a smaller band size. If, on the other hand, you find that the loosest hook feels too tight, you may need a larger band size.
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   Ensure you can slide only one finger below your bra strap. According to image consultant and style advisor Jordan Stolch, you should be able to fit one finger under your bra strap while wearing it. "No more than that," she says, or your bra is too big.

   • Tip: If the straps are loose when you first try on your bra, try tightening them first before giving up and sizing down. Similarly, if they're too tight, see if you can loosen them before sizing up.
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   Try on new bras before buying them, since bra sizing isn't standardized. "If you go to Victoria's Secret and then you go to La Senza and you go somewhere else, [the bra sizes are] all going to be different," says board-certified plastic surgeon Asif Pirani, MD. He also adds that a lot of stores that sell bras "inflate the size because when women, especially younger women, go to the bra store and they buy a bra and all of a sudden they used to be in a C and at this store they're a D, they want to buy more bras." Measure your bra size before you go shopping, and try on a range of sizes to find the one that fits best.
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