average breast size

Average Breast Size In America & Boob Sizes Chart

What’s the average bra size?

That’s a tricky question to answer, because it depends on a few factors such as age and whether we’re talking natural, pre-surgery sizes only (over 400,000 women in the US had a breast augmentation in 2018 alone). Oh, and not to mention that the average breast size in America is 34DD, but is not necessarily the same in other countries.

This article aims to explain exactly what determines your breast size, break down the average cup size and overall most common breast size around the world, and introduce you to the various bra styles that can make your bust look bigger or smaller. 

Average breast size by age (teens to adulthood)

average bra size

The teenage years are a delicate, confusing time for both boys and girls. Girls, however, are forced to face a number of body-image issues as they grow and change throughout their adolescent years. Many young women get caught up with obsessing over their looks, their weight, and their size.

Back before everyone had an iPhone in their pocket, we blamed the magazines and the runways. In 2019, it’s all about social media. Instagram stars and influencers are abound looking ever so exquisite, yet effortless with their taut skin and hourglass curves that boast rock-hard abs, tiny waists, and perky breasts and bottoms.

It’s no wonder teenage girls want to emulate their so-called flawlessness while being too young to realize exactly how unattainable this kind of ‘perfection’ actually is. What’s worse? Teenage bodies are hardly finished developing. How a girl looks at 12, and then at 15, and then at 17 can often look like three completely different women.

Although a woman’s breasts are usually fully-formed by the time she finishes puberty (which usually implies to a 14 year old, 15, 16 or 17 year old), that’s not to say that her bra size then is the one she’ll wear for the rest of her life. Breasts change size and shape throughout life – and even on a monthly basis, as they can swell slightly during menstruation.

It’s especially difficult to calculate the average bra size among teenagers, because puberty can hit at wildly different times. At age 7, 15% of girls are already developing breast tissue. By age 8, that figure rises to 25%. And yet there are others who make it to 12 or 13 with no signs of breast growth at all. It’s perfectly possible for one teen to be wearing an ‘adult’ bra while many of her peers are still in a training bra, or not needing to wear a bra at all. 

Going later into life, the average breast size among women in their 20s, 30s and 40s will be smaller than for women in their 50s and beyond. That’s because of the menopause, which tends to begin between ages 45 and 55. It causes a slowing of the metabolism, which in turn can lead to weight gain. According to a 2004 study, around 1 in 5 women will wear a larger bra size post-menopause than they did beforehand.

No one seems to have studied bra size by age in depth. But it seems safe to surmise that the average size will gradually increase with age – with perhaps a spike in the twenties and early thirties, since this being when many women become pregnant and see their cup size temporarily skyrocket.

Average cup size in America and other countries:

Just as the average clothing size varies around the world, so too do boob sizes – rather a lot! An extensive study of over 340,000 women measured the average cup size of people born in 108 countries, and found that it varied from below an A to above an F (US DDD). Here are some of them:

Average cup size in Australia: D
Average cup size in Brazil: B
Average cup size in Canada: DD
Average cup size in France: A
Average cup size in Germany: D
Average cup size in Ireland: D
Average cup size in Italy: A
Average cup size in Japan: A
Average cup size in Mexico: B
Average cup size in New Zealand: D
Average cup size in Russia: B
Average cup size in Singapore: < A
Average cup size in Spain: C
Average cup size in UK: D
Average cup size in USA (Caucasian): > DDD
Average cup size in USA (non-Caucasian): DD

Women in South Asia and South-East Asia tend to have the smallest cup sizes. Although some countries were excluded from this study, including China, throughout Japan, Singapore, Taiwan, Thailand, Malaysia, Indonesia and Cambodia the average cup size was always an A or below. Unsurprisingly, this general region is known for its ultra-padded, ultra push-up bra styles!

The largest (popular) average cup size was found in the USA, specifically among Caucasian women. This was the only group in the study where the average size was above a DD.

However, it is important to note that not all boob sizes, like ‘D cups’ are the same size. A 36D is bigger than a 34D in the band and cup, and has the same amount of breast tissue as a 38C. We’ve explained why in detail in the ‘sister sizing’ section of our bra size chart page.

Therefore, it’s better to look at the average boob size in terms of volume, and not just the average cup size. Luckily, the same study also involved measuring breast volume in milliliters.

Average Breast Size By Country (mL)

average breast size

Boob Sizes

boob sizes

You’ll notice for example that the average breast volume in Ireland is significantly higher than in Germany, despite both countries having an average cup size of D. Although the study did not include band size data, this suggests that in Ireland, the average band size is larger – a 36D for example rather than a 34D. As just mentioned, ‘D cups’ are bigger when they’re on a bigger band size.

Note that both boob size charts above are based on measurements taken from women aged 28-30 only (who were neither pregnant nor lactating, and who had not undergone breast surgery of any kind). So although they are very useful for comparing cup and breast sizes between countries, they don’t necessarily represent the average size in each country overall.

So what is the overall average? Well according to one study of 60,000 people, the average bra size in America is a 34DD. That’s up from a 34B two decades ago.

However, at least part of that increase can be attributed to better education on bra sizing, and the fact that it’s far easier nowadays to find a bra in a D+ cup size. Fewer full-busted women today are wearing a too-small cup size by mistake, or trying to cram their breasts into one simply because nothing bigger is available. And given that the average band size hasn’t changed, it seems American women haven’t really gotten much bigger.

lady holding coconuts on boobs

What determines your breast size?

Why do some women wear a AA cup, and others wear a GG? Overall weight is a factor of course – but then of course, there are both thin women with naturally large breasts and plus-sized women with small ones.

As explained further above, age plays a role in determining your bra size. A woman in her fifties or sixties is more likely to be full-busted than a 17 year old fresh out of puberty.

Pregnancy is also a factor. Not just lactation itself, which can easily cause an (albeit temporary) increase of two to three cup sizes, or even more. But also whether you’ve been pregnant in the past – some women’s breasts stay larger after they’ve finished breastfeeding, but many find that theirs shrink down to smaller than their pre-pregnancy size.

Mostly though, it just depends on your genetics. Despite claims to the contrary, there are no pills you can take, creams you can use, or exercises you can do to increase your breast size (although building up your pectorals muscles that sit below the breasts can make them look a tad bigger). If your mother had an especially small or large chest, or experienced a particular change in cup size after having you, there’s a good chance you’ll follow suit.

woman with cleavage

Bra styles to make your breasts look bigger or smaller

Not happy with your natural bust size? If you’re looking for a less invasive solution than surgery, you may be surprised at just how much of a difference changing bra styles can make. 

Bras to make your boobs look bigger

Molded cups – although these don’t actually add much volume, they give you a rounded shape that we tend to associate with the ‘fullness’ of larger breasts.

Padded bras – usually made with foam or gel, these have padding hidden away inside the cup to give the impression of extra volume. Depending on how much padding there is, you can look anywhere from 1 to 3 cup sizes bigger.

Push up bras – a specific type of padded bra, these have the most padding at the base of the cup. Your breast tissue sits on top of it, lifting it higher for more obvious cleavage.

Bras to make your boobs look smaller

Minimizer bras – specifically designed for just this purpose, these use tall, non-stretch cups that keep your breast tissue compressed, for a flatter profile. They tend to make your bust appear about one cup size smaller.

Bralettes – a wire-free, often unpadded style of bra, these offer less lift and a more natural shape. Although they don’t ‘squish’ your breasts at all like a minimizer, many women think their bust looks smaller in a bralette.

Bandeaus – essentially a tube of fabric, this basic bra style doesn’t have separate cups or underwires. The lack of support and lightweight compression combine to give your bust a slightly flatter appearance. 

Need help with bra measurements? 

Try our size chart / calculator

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