Sister Sizes: Secrets from the Fitting Room

When it comes to finding the perfect bra, most women focus on their usual size, like 36C or 34D. However, what many don't realize is that bras come with "sister sizes"—a concept that can make a world of difference in achieving the best fit. Understanding sister sizes can be a game-changer for anyone struggling to find a comfortable and supportive bra.

What Are Sister Sizes?

Sister sizes are bra sizes that have the same cup volume but are actually different sizes. For example, if you usually wear a 34C but find the band too tight, you can try a 36B. The volume of the cup size will remain the same, but the band will be more comfortable. Conversely, if the band is too loose, you might try a 32D. Here’s how it works:

 Cup Volume

The letter in your bra size (C, D, G, etc.) indicates the cup volume. Sister sizes share the same cup volume but differ in band size, which is the number part of your bra size.  This number represents the measurement around your ribcage. Sister sizes move up or down in band size, altering the number while keeping the cup volume consistent.  

How to Find Your Sister Size

To determine your sister size, you simply need to adjust the band size and cup size simultaneously:

• If your band size is too tight, Go up one band size and down one cup size. For example, if you wear a 34C, try a 36B.
• If your band size is too loose, Go down one band size and up one cup size. For example, if you wear a 34C, try a 32D.

Why Does it Matter? 

Understanding sister sizes can be particularly helpful in several scenarios:

• Weight Fluctuations:  If your weight changes, your band size might need to be adjusted, but your cup volume could stay the same. Sister sizes allow you to find a new fit without sacrificing comfort or support.
• Limited Stock: Sometimes, your preferred size might be out of stock. Knowing your sister size gives you more options without compromising on fit.
• Better Fit:  Different brands and styles may fit differently, even in your usual size. Experimenting with sister sizes can help you find the perfect fit across different brands.
• Comfort:  If you’ve always felt that your bra was either too tight or too loose but haven’t found a better size, trying a sister size might resolve your discomfort.

 Tips for Shopping Using Sister Sizes

 Try Before You Buy:  Always try on bras before purchasing, especially when experimenting with sister sizes. Different brands can have slight variations in sizing. We recommend you get a bra checkup annually to see if your bra size has changed, or you require a new style.

 Check the Fit: Ensure the band fits snugly around your body without riding up, and that the cups fully contain your breasts without spillage or gaps. Reminder: 90% of the support of your bra comes from the band fitting snugly around your rib cage.  You should be able to slip 2 fingers under the band, signaling a proper fit.  

Don't Be Afraid to Experiment- your perfect bra might not be in your usual size, but in a sister size that offers better comfort and support.

Sister sizes are an often-overlooked secret in the world of bra fitting. By understanding and using sister sizes, you can expand your options, improve your comfort, and finally find the perfect bra that makes you feel supported and confident every day. Next time you're bra shopping, keep your sister sizes in mind—you might just find your new favorite fit!

Be Uplifted!

Your Fairy Bra Mother

Lori Kaplan