Bra Sizing

There is so much confusion around bra sizing—and it’s not unwarranted! Bra sizing is neither simple nor intuitive, and instead is confusing and totally convoluted! It’s also often different depending on the brand. We get a ton of questions about bra sizing, how it works, “if I’m this, then am I this?”, etc., so we’ve created this guide to hopefully clear up some of the confusion, and ideally help you to find your best fit—being it a Maman Atelier bra or one made by any other brand. <3 

  1. Find out your true measurements:  Opt for a flexible tape measure that can wrap around your body easily. The following two measurements will help you best determine your size.
    First, you will take your underbust measurement to find your band size. Wrap the tape measure around your ribs just under your breasts (take this measurement on an exhale, not when your lungs are full and expanded). Underbust MeasurementThe second measurement is your bust measurement. This is achieved by wrapping the tape measurer around your back and the fullest part of your breasts.Bust Measurement
  1. Your band size is not the same as your underbust measurement. This is really important and frequently where so much of the confusion in bra sizing stems from. In Imperial Sizing, what is most commonly used in the United States and the UK ( 32B, 30C, 34D, etc.), you must add 4-5 inches to your underbust measurement to arrive at an even number to get your band size. So if your usual bra size is a 34B, that means your actual underbust measurement is likely 29-30 inches. Very few brands in the US use the exact measurement of the underbust as the band size, and if they do, they’ll most likely tell you.
  1. You are not your cup size. It’s all about the ratio. Your cup size is determined by finding the difference between your bust measurement and your band size (again, not to be confused with your underbust measurement). In imperial sizing, for each inch difference, you increase a cup size starting with A.
    Here’s an example: Your underbust measurement is 31”, which means your band size is 36”. If your bust measurement is 39”, then 39-36 = 3”. With a difference of 3”, your cup will be a C, giving you a bra size of 36C. This is a great starting point, but what if you prefer your band a bit more snug? (This can be particularly helpful with soft or wireless bras.) So you try a 34” band, but what cup size to take? This is why it is important not to get attached to a certain cup size—the cup on a 34C will be smaller than the cup on the 36C, so you’ll need go up in cup size and try a 34D. This concept is called Sister Sizing and you can use it as a tool to find your best fit. To try a sister size, decrease your band size by 1 while increasing cup size by 1, or vice versa, increasing band size by 1 and decreasing cup size by 1. This way, you have a range of sizes you know may fit you well, and within them you can find your favorite fit!
  1. Wear what you feel best in. So, you take your measurements and they tell you what your bra size should be. That’s really great, but that’s only part of the solution. Like your favorite pair of jeans, you probably like your bra to fit and make you look a certain way. Your style, comfort and support preferences, and lifestyle will all come into play. Maybe you like your bra to fit snug around the band and tighter in the cups, so try taking the smaller size. Perhaps you prioritize absolute comfort and are working from home, maybe you don’t even usually wear a bra but want a little something—trying the larger size in this case could be a good choice. The point is that it is your decision! Wear the size that fits you and your needs & desires best. 
  1. Bra sizing differs from brand to brand. You probably wear a couple different bra sizes depending on the style and brand. Unfortunately, even with the broad acceptance of the Imperial Sizing systems, the reality is that there is no standard or completely universal system of measurements that every brand and bra maker follows. Most companies have unique size charts and fitting guides tailored to their unique patterns and design. So, A 36C in one brand will likely fit differently than that same size in a different brand.
  1. Your bra size can (and most likely will) change. As time passes, our bodies change. Sometimes these changes can occur on shorter timelines—perhaps on a monthly basis as you move through your cycle, or on a longer-term scale such as gradual weight gain or loss over the course of years. Because of this, it’s not a bad idea to check in from time to time and reevaluate if your usual size, fit, or style is working for you. The point is not to get too attached to a certain size. It’s about feeling comfortable, sexy, and confident, and finding the size and styles to make that happen!


That’s a lot of general background and reflections on standard bra sizing. You may have noticed that our sizing is XS-XL, with no mention of cup or band sizes. So how do you find your best fit in Maman Atelier? The best place to start is by determining your measurements, and then referring to our size chart:

Maman Atelier Size Chart


This will give you a great idea of which size will fit you best. If you find that you are in between sizes, consider point #4 in the guide—what do you feel best in? Do you want your bra to be more snug, or would you prefer a little more room? What sizes do you generally wear in tops and dresses? If you usually take a medium, it’s likely that a medium bra will suit you well—unless you prefer your clothes oversized! In short, there is often no simple answer, but the hope is that in reading this you’ve learned something new and realized that bra-sizing is a bit of a process (or journey even), and that’s ok.