Shop Now New Bras Undies Lingerie Fit Blog Loyalty Program

36dd sister size

I’m sure I’m not the only one who has wondered, “how do bra sizes work?” Learning how to read a bra size tag doesn’t have to be difficult. If you feel confused in a sea of different letters and numbers, you are not alone. Bra sizing is difficult. Not only is it difficult, but so many women wear the wrong size bra, making a bra fitting important.

Understanding Band/Cup Sizes

Traditional bras include a letter and a number, for example 38C. The number represents the band size and the letter, the cup size. To get this number, measure tightly around the bottom of a bra band while wearing it. Round to the nearest whole number. Add two if the number is even and three if the number is odd. This is known as your band size.

In terms of the cup size, measure around your chest again placing the measuring tape at the fullest part of the bust. The tape measure should be parallel to the floor. Subtract your band size from your bust size. If the difference is 1, your cup size is A and so on. This measurement refers to the size of your breast in relation to your rib cage. It’s important to note that some bra fitting experts don’t agree with this method of measuring your cup size and suggest trying on different cup size bras to find the best fit for your particular bust. Ultimately, cup size doesn’t represent volume, but instead the different between the dimensions of the breast and the rib cage. It is not possible to determine someone’s true breast size by their cup size along.

Remember that this is a guide. Bra sizing isn’t standard and like clothing designers, bra manufacturers will determine their own fit. You may wear a different size in different brands, so regular sizing is important. Also, don’t assume your bra size will always remain the same. Losing weight, becoming pregnant or breastfeeding are all instances that may affect your bra size.

Related Post: 7 Signs You Are Wearing The Wrong Bra Size

bra sister sizes

Mod By Parfait Sweetheart Padded Bra A1391 | Mod By Parfait Sweetheart Hipster A1395 in Bright White/Almond Blossom

How Does Sister Sizing Work?

Bra sizes that are similar in breast volume are referred to as sister sizes. These sizes demonstrate that if your bra cup fits your breast perfectly, but you need a different band size (because it is too loose or too tight) that you will need to change your cup size to achieve the same fit. One’s sister size will depend on their current cup size and the fit of their bra.

Learning your sister size can be determined by a few questions:

Do your cups fit seamlessly and smoothly without spilling?

If yes, continue on, if no, then your bra cups aren’t fitting as they should and you need a professional bra fitting.

Which hook setting do you use?

If the tightest, sister size up (One size larger than your current bra and one letter up). If you use the loosest, sister size down (one size smaller and one letter larger).

Ultimately, having a bra that fits is important and can be a stressful journey. In reality, more than one size bra may fit you. That should be exciting, but to many, it just means a longer hunt to finding the dream bra that does the job right the first time. Understanding all the components to a proper bra size and fitting will help you get closer and closer to that perfect fit. Learning how to read a bra size tag and how sister sizes work are just two more life lessons for girls to master in their lifetime. I’m still working on it! Happy bra shopping!

How do you find a bra that fits? A bra fitting specialist can help you find the proper bra and to understand how do bra sizes work. Visit our specialty store locator to find a store near you and schedule an appointment.

Related Post: 6 Bra Care Tips You Probably Didn’t Know

We Highly Recommend

Whether you’re shopping for new everyday bras or lingerie for a special occasion, it’s always a good idea to seek out a second opinion. We know how hard it is to find bras that fit well and feel good, especially when you’re doing it on your own. If you’ve ever felt unsure about your bra size or you just don’t know where to go to find good bras, it’s time to let a bra fitter help.

Many specialty lingerie boutiques offer bra fittings. Their expert bra fitters will take the pain and frustration out of bra shopping and do all the work for you. Even better, their product knowledge can save you time and money. Plus, they know where all of the best bras are hiding.

If you’ve struggled with finding bras in the right size, it’s time to make a change. Visit our specialty store locator to find a store near you and schedule an appointment.

Happy bra shopping!

Featured image lingerie:
Mod By Parfait Sweetheart Padded Bra A1391 | Mod By Parfait Sweetheart Hipster A1395 in Bright White/Almond Blossom


Shop Now

Published by

Katie Donnelly

Katie Donnelly is a full-time freelance writer, content manager, and founder of Katie Rose Creative. An experienced bra fitter, Katie has helped hundreds of people shop for lingerie. Her favorite bra is the Sandrine Plunge Longline Bra.

Go Top