How Common Is Your Bra Size? The Facts Explained

It is a core human experience to look at yourself and wonder, am I normal? The truth is, there’s no normal, there’s only average or common — and that average size is only an estimate, and it changes all the time. Today, we’re gonna talk about average breast size and why breast sizes change. 

What is the Average Bra Size in the US?

Before we dive in, it’s important to note that it’s difficult to get 100% accurate reporting on bra size since it’s primarily done via self-reporting, which means there’s a risk of reporting errors (after all, 80% of women are wearing the wrong size). However, one of the best and most recent surveys conducted was by the brand Intimacy, which surveyed 40,000 women and found that the average bra size was 34DD — up from 34B just 20 years prior. More recently, Bedbible surveyed over 15,000 women worldwide and found the average US bra size to be 40C.

How Has the Average Bra Size Changed Over Time?

The average bra size has been steadily increasing over the past few decades, and although we don’t know definitively why this is happening, there are some very likely factors contributing to this trend. One reason for larger bra sizes is likely due to the rise in average BMI across the population. As bodies get bigger overall, breast size tends to increase proportionally. 

Another factor is the expansion of size ranges offered by lingerie brands. In the past, women with larger busts often struggled to find well-fitting bras in their size. However, as brands have become more inclusive and begun offering a wider variety of sizes, more women are able to find their true size rather than having to squeeze into a size that’s too small. This has resulted in a larger range of bra sizes.

Additionally, the popularity of breast augmentation surgery has been on the rise in recent years. As more women opt to surgically enhance their bust size, this may contribute to a larger average cup size within the population. While not all women who undergo breast augmentation end up with significantly larger breasts, the overall trend could have an impact on the average bra size.

What Factors Influence Bra Size?

Several key factors play a role in determining an individual's bra size. Genetics are a significant influence, as family history and hereditary traits heavily impact breast size and shape. Some women are simply predisposed to having larger or smaller busts based on their genetic makeup.

Weight and exercise also contribute to bra size fluctuations. Since breasts are primarily composed of fatty tissue, changes in body weight can directly affect breast size. Maintaining a stable weight through regular exercise can help minimize these fluctuations and promote a more consistent bra size over time.

Environmental factors may also play a role in breast size, although research in this area is limited. Some studies suggest that diet, particularly the consumption of foods high in estrogen, may impact breast development and size. Additionally, the use of hormonal birth control has been linked to temporary increases in bust size for some women.

Is It Normal for Breast Size to Fluctuate?

Absolutely! Women's breast size can change not only day-to-day but also throughout various life stages. During the menstrual cycle, hormonal changes can cause temporary breast swelling and tenderness, which may make bras feel tighter or less comfortable for a short period. 

Pregnancy and breastfeeding also impact breast size. Breasts often increase in size during pregnancy due to weight gain and hormonal shifts. Milk production post-delivery can further increase bust size until weaning occurs.

As women enter menopause, they may also experience a decrease in bra size. As estrogen levels drop during this stage, it's a natural part of the aging process and may require adjusting bra size and style to maintain comfort and support.

Putting Bra Size in Perspective

At the end of the day, it's important to remember that every body is unique, and there is no such thing as a "normal" or "ideal" bra size. Bra sizes exist on a wide spectrum, with many women falling above or below the average.

Instead of focusing on fitting into a certain size, prioritize finding a comfortable, well-fitting bra that supports your individual shape and needs. Use a reliable bra size calculator to determine your measurements, but don't get hung up on the numbers.