e cup boobs

Large Breasts: E Cup through K Cup Boobs

Full Bust Guide – What Large Cup Sizes Really Look Like

There’s a lot of misinformation out there about big busts and bra sizes. Even what society thinks of as ‘big breasts’ and what the lingerie industry actually counts as a full-bust size can be quite different!

Did you know for example that:

  • The number in a bra size doesn’t say anything about the size of the breasts?
  • The largest bra size is well beyond a DD cup?
  • ‘DD’ isn’t even a specific size, since a 34DD person has larger boobs than a 32DD person?

This article explores everything from how big each cup size actually is to which bras are best for big busts. Read on to learn the truth about having and shopping for big breasts!

How does cup sizing work?

breast size guide

A bra size contains a number and letter. Only the letter – aka ‘cup size’ – relates to the breast size, while the number indicates the size of the ribcage below.

Cup size is measured as the difference between the ribcage and around-the-bust measurements. In other words, it tells you how far out the breasts stick from the body. Every 1” of difference equals one cup size – A = 1”, B = 2”, etc. Anything above a D cup is counted as a ‘full bust’ by lingerie brands.

However, what cup size doesn’t tell you is how wide the breasts are. A 40F wearer will have much larger boobs than a 30F wearer, because the 40F wearer has a wider body and hence wider boobs.

What is the largest bust size?

Theoretically, there’s no limit to how large cup sizes get can. But in practice, the biggest bra size you can find easily online is a US I cup, and the largest bra size you’ll find with some effort is around a US O cup. 

Beyond that, for exceptionally large cup boobs, you may need to look into getting custom bras made.

What causes large breasts?

how big are large cup sizes

Often, bigger busts are simply the result of genetics. If other women in your family have large boobs, chances are you will too.

However, certain medications, thyroid conditions, weight gain due to the menopause, and weight gain in general can all cause your bust to expand too. 

Plus of course, pregnancy! Your bra size will fluctuate throughout your life, but most women will experience their largest bust size while nursing. The breasts are plumped up with milk, which also makes them extra heavy! 

Pros and Cons of Bigger Busts

Some full-busted women view their chest as a blessing. Others see it as a curse. It all depends on your viewpoint:

Beauty – for better or worse, our society prizes large breasts as being attractiveUnwanted attention – especially from men, but even women may assume you are ‘flaunting’ your chest when it just looks that way in any outfit
Confidence – linked to the above, a large bust can make you feel sexier and hence more confidentPain – your back especially can tire from supporting all that weight
Portable storage – okay, a bit of a jokey one, but all full-busted women have used their cleavage as a pen holder at some point!Plainer, more expensive bras – it’s undeniably harder to find stylish bras in large cup sizes. They are also harder to design and make, so tend to cost more

Now, time to learn about each larger bust size individually:

Large Boob Cup Sizes:

E Cup Breasts

What is an E cup breast size?

A US E cup size means that the overbust measurement (the fullest part of the breasts) is 5” larger than the underbust (ribcage) measurement.

How big is an E cup?

E cup boobs stick out around 5” from the ribcage. However, E cups on larger band sizes are larger overall, as they are wider.

Example E cup measurements

30” underbust + 35” overbust = 30E

34” underbust + 39” overbust = 34E

37” underbust + 42” overbust = 38E

What do E cup breasts look like?

How big E cup boobs look, and how much space is inside the cups of E cup bras, depends on the band size. Below is a comparison image of a US 30E (left) and US 36E (right):

E cup breasts
Images via Bratabase

Is an E cup the same as a DD, or is DD bigger/smaller?

E cups vs DD in America: In the US, E and DD are just different names for the same cup size. Some brands prefer a D-E-F sizing system, while others prefer a D-DD-DDD one. 

E cups vs DD in the UK and Australia: Here, an E cup is one size larger than a DD, since the sizing system goes D-DD-E.

E cup sister sizes

The two E cup sister sizes are D (when you go up one band size) and F/DDD (when you go down one band size).

For example, the sister sizes of 34E are 36D and 32F/DDD.

Best bras for E cup breasts

E cups are a full-bust size, but one of the smaller ones. Therefore, they don’t always need bras designed for heavy-duty support, especially on the smaller band sizes. 

Here are two popular E cup bras:

F Cup Breasts

What is an F cup size?

In the US, an F cup size indicates that the overbust measurement is 6” larger than the underbust one.

Example F cup measurements

30” underbust + 36” overbust = 30F

35” underbust + 41” overbust = 36F

42” underbust + 48” overbust = 42E

Here are two examples of F cup breasts on different band sizes – a US 30F (left) and US 36F (right):

f cup boobs
Images via Bratabase

Is a DDD the same as an F?

F cups vs DDD in America: Again, due to the two sizing systems in the US (D-E-F vs. D-DD-DDD), these are just different labels for the same thing.

F cups vs DDD in the UK and Australia: In these countries, there is no such thing as a DDD cup size. However, their F cup bras are one size bigger than a US F cup (so are equivalent to a US DDDD cup).

What is the difference between F and FF cup breasts?

Firstly, an FF cup size does not exist in the US. There, the only letter that gets doubled (and tripled, and quadrupled…) is a D. It also doesn’t exist in mainland Europe, since they do not use any double-letter sizes.

FF is a UK/Australian size. It’s one size larger than their F cup size, and one size smaller than their G cup size. The US equivalent of a FF cup would be an H or DDDDD.

What is the difference between FF and G cups, are they the same?

As explained above, UK/Australian double letters sit between the single version of that letter, and the following letter in the alphabet. So no, FF and G cups are not the same – the G is one size larger.

F cup sister sizes

The F cup sister sizes are E/DD (when you go up one band size) and G/DDDD (when you go down one band size).

For example, the sister sizes of 30F are 32E/DD and 28G/DDDD.

Best bras for F cup boobs

Like E cups, F cup breasts are one of the smaller full-bust sizes. Therefore, F cup bras with only minimal tweaks for added support are often sufficient. For example, horizontal and vertical seaming that divides the cup into 3 sections (known as ‘3 part cup’ bras).

Here are two great bras for F cup boobs:

G Cup Breasts

What is a G cup size?

In US bra sizing, a G cup size means that the person’s overbust measurement is 7” larger than their underbust one. 

Example G cup measurements

26” underbust + 33” overbust = 26G

31” underbust + 38” overbust = 32G

40” underbust + 47” overbust = 40G

Here are examples of G cup breasts on two different band sizes – a US 30G (left) and 36G (right):

g cup boobs
Images via Bratabase

Is cup size GG bigger than G?

Yes, a GG is one size larger than a G. However, this is only the case in the UK and Australia, since GG doesn’t exist as a cup size in the US. There, the next size after a G is an H.

What is the difference between a G cup and a FF?

G cup vs FF in the UK/Australia: A FF is one size smaller than a G.

G cup vs FF in the US: FF is another size that doesn’t exist in the US. However, its equivalent would be a US H cup. In other words, it would be one size larger than a US G cup.

Check out the international cup size conversion chart on this page if you’re confused!

What do G cup breasts weigh?

The weight of G cup breasts varies, since their size does. G cup boobs all ‘project’ the same amount, but on a smaller band size they are narrower, and therefore smaller overall.

According to Hourglass Lingerie:

  • 28G breasts weigh about 1.2lbs each
  • 30G breasts weigh about 1.5lbs each
  • 32G breasts weigh about 1.7lbs each
  • 34G breasts weigh about 2lbs each

They also explain how to measure yourself using the ‘water displacement’ technique, if you want to know exactly what your own G cup boobs weigh!

G cup sister sizes

The G cup sister sizes are F/DDD (when you go up one band size) and H (when you go down one band size).

For example, the sister sizes of 40G are 42F/DDD and 38H.

Best bras for G cup breasts

Although smaller full-bust sizes can sometimes get away with wearing ‘regular’ bras, a US G cup is around the breast size where you will definitely need to look for bras with at least a few supportive elements. For example, look for G cup bras with wider bands, wider straps, and/or 3-part cups.

Here are two G cup bras we recommend:

H Cup Breasts

What is an H cup size?

A US H cup size means that your overbust measurement is 8” larger than your underbust one. 

Example H cup measurements

27” underbust + 35” overbust = 28H

30” underbust + 38” overbust = 30H

42” underbust + 50” overbust = 42H

Here’s a side-by-side comparison of H cup breasts on two different band sizes – a US 30H (left) and 36H (right):

H cup boobs
Images via Bratabase

Is H cup big?

Yes is the simple answer. Full-bust sizing begins at a US E cup (though some full-bust brands start from a D), so an H is well into full-bust territory. H cup boobs vary in size depending on the band size (e.g. 40H is bigger than 30H), but will never look small.

Is H cup bigger than DDD?

Some US brands use a D-E-F sizing system, while others use a D-DD-DDD one. This means that a DDD equals a US F. Therefore, yes, H cup breasts are (two sizes) bigger than DDD ones.

How much do H cup boobs weigh?

H cup breasts all ‘project’ 8”. However, the larger the band size (and hence body), the wider the breasts and the more they weigh. According to the same article linked above:

  • 28H breasts weigh about 1.5lbs each
  • 30H breasts weigh about 1.7lbs each
  • 32H breasts weigh about 2lbs each

H cup vs. G – 28G breasts weigh approximately 1.2lbs each, hence by going up one cup size you are carrying around an additional 0.6lbs or so!

H cup vs. I – 28I breasts weigh roughly 1.7lbs each, so are around 0.4lbs heavier than a 28H bust.

H cup breast reduction surgery

In the US in 2018, over 43,000 female breast reductions were carried out, so it is not an uncommon procedure. However, it is an invasive surgery that carries some level of risk.

If your chest is causing you back or neck pain, the first step should be to check if a better bra can solve it. Good H cup bras (that fit well) will distribute the weight of your bust around your body, reducing strain on your shoulders. 

H cup sister sizes

The H cup sister sizes are G/DDDD (when you go up one band size) and I (when you go down one band size).

For example, the sister sizes of 36H are 38G/DDDD and 34I.

Best bras for H cup size

As well as the support features already mentioned, you may want to look for bras with a side support panel – when there’s a lot of breast tissue, this helps to bring it forwards, away from the underarm.

Here are two H cup bras with side support panels:

I Cup Breasts

What is an I cup?

A US I cup size is one where the overbust measurement is 9” larger than the underbust one. 

Example I cup measurements

32” underbust + 41” overbust = 32I

39” underbust + 48” overbust = 40I

42” underbust + 51” overbust = 42I

How big is an I cup size?

I cup breasts will be larger on larger band sizes than on smaller ones. However, as they stick out roughly 9” from the body, they are definitely a cup size that looks big.

I cups vs. H cups – I cups are one size up from an H, so while bigger, but the difference is not dramatic.

I cups vs. E/DD cups – although both of these are full-bust sizes, I cups add an extra 4” to the overbust measurement compared to an E, so will appear significantly larger! 

Here are examples of I cup breasts on different band sizes – a US 30I (left) and US 36I (right):

i cup boobs
Images via Bratabase

How much do I cup breasts weigh?

I cup boobs will weigh more or less depending on their size, since they are larger (wider) on a larger band size.

For example, according to the Hourglass Lingerie article:

  • 28I breasts weigh about 1.7lbs each
  • 30I breasts weigh about 2lbs each

I cup breast reduction surgery

I cup boobs weighing you down? As explained above, breast reductions are a fairly common surgical procedure, but it is worth investigating whether problems such as back pain can be solved through simply switching bras.

Well-made, supportive I cup bras aren’t particularly cheap, but they certainly cost less than a breast reduction! 

I cup sister sizes

The I cup sister sizes are H (when you go up one band size) and J (when you go down one band size).

For example, the sister sizes of 34I are 32J and 36H.

Best bras for I cups

The best I cup bras have support features beyond what you’d find in a DD cup bra. For example, the cups may have thicker, sturdier underwires. Or they may have multiple vertical seams rather than just one, to reinforce support and add more lift.

Here are two great I cup bras:

J Cup Breasts

What is a J cup?

In the US, a J cup size means that your overbust measurement is 10” larger than your underbust one. 

Example J cup measurements

30” underbust + 40” overbust = 30J

33” underbust + 43” overbust = 34J

42” underbust + 52” overbust = 42J

Below is a comparison of J cup breasts on different band sizes – a US 30J (left) and US 36J (right):

j cup boobs
Images via Bratabase

US J cups vs. UK J cups

Although most brands don’t continue with ‘D’ sizing beyond a G/DDDD, some do, and a US J cup is also sometimes known as a DDDDDDD or ‘7D’ cup. That makes it six sizes beyond a D.

In contrast, a UK J cup comes after a UK HH cup (there is no ‘I’ in UK cup sizing), which is nine sizes beyond a D. UK and US D cups are the same, hence when you are comparing US vs. UK J cups, the UK J is much larger.

How much do J cup breasts weigh?

According to the Hourglass Lingerie article referenced above, 28J breasts weigh approximately 2lbs each. But 28 is a small, fairly uncommon band size, so most J cup boobs will weigh more! The larger the band size, the wider the breasts and the more breast tissue they will contain.

J cup breast reduction surgery

If you have J cup boobs that are causing you considerable back or neck pain, then you are likely a good candidate for breast reduction surgery.

However, pain from heavy breasts is often caused by poorly-fitting bras. The band should provide around 80% of the support, but many women wear a band size that’s too loose to do its job correctly. 

So before you make an expensive and invasive decision, it pays to have a professional bra fitting and see if better-fitting, better-made J cup bras could quite literally take that weight off your shoulders.

J cup sister sizes

The J cup sister sizes are I (when you go up one band size) and K (when you go down one band size).

For example, the sister sizes of 36J are 38I and 34K.

Best bras for J cups

J cup breasts are heavy, so the best J cup bras are designed first and foremost with support in mind. But that’s not to say that you can’t find pretty ones!

Here are two J cup bras that are supportive and stylish:

K Cup Breasts

What is a K cup size?

In the US sizing system, a K cup size indicates that the overbust measurement is 11” larger than the underbust measurement.

Example K cup measurements

28” underbust + 39” overbust = 28K

34” underbust + 45” overbust = 34K

47” underbust + 58” overbust = 48K

Here is a quick comparison of K cups on different band sizes – a US 30K (left) and US 36K (right):

k cup boobs
Images via Bratabase

How much do K cup breasts weigh?

Unfortunately, there is not much data available about how much K cup breasts weigh. However, we can look at K cups. vs J cups plus K cups. vs I cups to get a general idea.

Considering that 28I breasts weigh roughly 1.7lbs per breast and 28J breasts weigh roughly 2lbs per breast, we can assume that each 28K cup breast would weigh somewhere in the region of 2.3lbs.

Of course, 30K breasts will weigh more than 28K breasts, as they are wider. And 32K breasts would weigh more than 30K breasts, and so on.

K cup breast reduction surgery

As with J cups, K cup boobs are very heavy whatever band size they’re on, but especially heavy on the larger band sizes. It’s imperative to seek out K cup bras that prioritize support, and ensure that you are not wearing a band size too large/loose for your needs.

However, should you still have back pain from your K cup chest even in a well-fitting and high-quality bra, you may want to consult a plastic surgeon to discuss a breast reduction. It’s one of the most commonly-performed surgeries, and highly effective at relieving pain and posture problems caused by plus size breasts.

K cup sister sizes

The K cup sister sizes are J (when you go up one band size) and L (when you go down one band size).

For example, the sister sizes of 40K are 42J and 38L.

Best bras for K cup breasts

The general guidelines when shopping for bras for K cup boobs are the same as for I and J cups. That is to say, look for wide bands, wide straps, seamed cups, and preferably some kind of side support. If the popular ‘3 part cup’ shape isn’t giving you the lift you need, you can find 4- or even 5-part cups in these larger sizes.

Here are two great K cup bras to check out:

Large Bra Sizes – Comparison

Below are all of the cup size images together for easy comparison. Are some of them smaller than you were expecting? A DD cup for example is often thought of as being the biggest bra size, yet breasts can get significantly bigger than that!

plus size breasts
Images via Bratabase


Whatever your cup size, we say embrace it! Pretty bras may be harder to find in larger cup sizes, but it’s not impossible. 

And if you’re suffering from breast-related pain, a high-quality bra that offers tons of support can really help. No, a chic and supportive bra won’t come cheap, but the comfort and confidence it brings is totally worth it.

P.S. Unsure of your cup size? Use our bra size calculator!

Do you want to have firm, perky breasts that feel and look great under any kind of clothing, whether it’s a sexy bikini on the beach or a cute sweater in winter that exudes warmth and romance? We recommend Brestrogen or Total Curve as the best natural breast enhancement cream & pill. Read this post for more.

Comments( 02 )

  1. Ok I just measured myself. It looks like I’m a 42H. But I can tell you now that my breast weigh 3.5 lbs each. And I need a good bra with major back support. I hurt all the time in my back. Upper and lower. However I can NOT do underwire. Pleaseeeeee help me find a bra. Im stuck wearing DDD because that’s the largest I can find. Thank you.

  2. There was a question above that asked how much a K cup sized breast weighed. Unfortunately, the comparison in K cups using band widths that are generally smaller do not give a full picture of how much a K cup sized breast can weigh for someone who is overweight or taller or both. In my case, I was a K cup size, but my band size was a 42. I was both overweight and tall. I did in fact have significant back pain, and I had a great deal of difficulty finding a properly fitting bra, and ended up opting for a breast reduction surgery. Once I had come out of surgery and stood up, the first things I noticed were that a) my back did not hurt, and b) my entire sense of equilibrium had changed. I was now reduced to a large B cup/small C cup breast size to give an idea of why there was such a significant change to my equilibrium. To further indicate why that happened, and to further answer the question posed above about the weight of a K cup sized breast, I was told a total of 10 pounds of breast tissue had been removed – that is 5 pounds per breast! Considering that I still had breast tissue enough to make up a B/C cup breast, this means that each K cup breast was still in excess of 5 pounds of weight.

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