K Cup Bras – Brands That Make K Cups & How to Find Your Size
Finding bras in a UK K cup can be challenging. Many high-street and mainstream brands stop well before this cup size, leaving women with limited choice or bras that lack proper support. This guide focuses specifically on K cup bras, showing which brands make them, what band sizes are available, and how to confirm your correct size before shopping.
To confirm your starting size, begin with our Bra Size Calculator, then explore the specialist brands listed below.
Who This Guide Is For
- Women who wear a UK K cup
- Fuller-bust and fuller-figure customers
- Those sized out of high-street brands
- Shoppers comparing specialist DD+ brands
- Anyone repeatedly sister-sized due to limited availability
Why Not All K Cup Bras Are the Same
Although K cup is a recognised UK bra size, the cup letter alone does not represent one fixed volume. Cup volume changes with band size, and some brands use different cup lettering systems when labelling equivalent measurements.
The K cup is part of the extended UK bra size sequence used by many fuller-bust brands. It sits between JJ and KK, with each step representing a one-inch increase in the difference between the bust and underband measurements.
K cup sizes are commonly found in specialist lingerie brands that offer a wider range of cup sizes than standard high-street collections. As with all bra sizes, the combination of the band size and cup size determines the overall volume.
If you are comparing neighbouring cup sizes, see our J vs JJ vs K Cup Size Comparison guide.
You can also explore our How Big Are K Cups? guide to see how K cup volume changes across different band sizes.
How Big Is a K Cup?
A UK K cup bra sits within the fuller-bust end of the extended UK cup size sequence. However, how large a K cup appears depends on factors such as band size, body proportions and bra design.
For example, a 30K and a 40K do not have the same cup volume. Cup volume increases as band size increases, which is why the cup letter alone does not tell the full story.
If you would like to see visual examples across different band sizes, visit our How Big Are K Cups? guide.
K Cup Size Progression
A K cup sits between JJ and KK in the extended UK cup size sequence used by many fuller-bust brands. The diagrams below show how cup volume increases gradually while the band size remains the same.
K sits between JJ and KK in the UK bra size sequence.
34JJ
34K
34KK
These simplified educational diagrams show how cup volume increases across nearby UK cup sizes when the band size stays the same.
Cup volume increases gradually across the UK sizing system. A 34KK has more cup volume than a 34K, while a 34JJ has slightly less.
How cup sizes actually work: Bra cup sizes are based on a simple fitting rule — each step in the cup sequence represents a 1 inch difference between the bust and underbust measurement. This rule applies across all UK brands, regardless of whether they use a traditional or extended cup letter sequence.
In brands that use an extended UK cup sequence, K is a separate cup size positioned between JJ and KK. Each step represents the same one-inch increase in measurement difference, making K one cup size larger than JJ and one cup size smaller than KK.
The difference between brands is the lettering used, not the size step itself. For example, some traditional UK cup sequences move directly from J to K, while extended UK sizing includes JJ and KK as additional cup sizes around K.
UK vs US Bra Sizes
Bra sizing systems vary slightly between regions. Most specialist fuller-bust brands such as Panache, Freya, Fantasie and Elomi follow the UK cup size sequence, which includes double letters such as FF, GG and HH.
Some US brands use a slightly different lettering system, which can create confusion when comparing sizes internationally. To understand how the sizing systems relate, see our UK vs US bra size comparison guide .
Is a UK K Cup the Same as a US K Bra Size?
It depends on the brand. Many UK-based fuller-bust brands such as Panache, Freya and Elomi use the same extended UK cup sequence internationally, meaning an K cup is labelled the same in both the UK and US.
However, some US lingerie brands follow a different cup progression. For this reason, always check the brand’s stated sizing system rather than relying on the cup letter alone.
A cup size is not one fixed volume. Cup volume increases as the band size increases, so a 30K, 34K and 40K are all very different in fit and capacity, even though the cup letter is the same.
Always consider both band size and cup size together when comparing bras.
Brands That Make UK K Cup Bras
- Bravissimo – Bands 28–40, cups D–L View size guide
- Elomi – Bands 32–46, cups D–K View size guide
- Panache – Bands 28–40, cups D–K View size guide
- Sculptresse – Bands 34–46, cups D–K View size guide
- Goddess – Bands 34–48, cups D–K View size guide
- Royce – Bands 28–48, cups AA–L (wire-free & specialist styles)
K Cup Band Sizes by Brand
- Bravissimo: 28K, 30K, 32K, 34K, 36K, 38K, 40K View size guide
- Panache: 28K, 30K, 32K, 34K, 36K, 38K View size guide
- Elomi: 32K, 34K, 36K, 38K, 40K, 42K View size guide
- Sculptresse: 34K, 36K, 38K, 40K, 42K View size guide
- Goddess: 34K, 36K, 38K, 40K, 42K, 44K, 46K View size guide
- Royce: 30K, 32K, 34K, 36K, 38K, 40K, 42K View size guide
K Cup Volume Changes With Band Size
Many people assume that all K cups are the same size. In reality, cup volume increases as band size increases. A 38K holds more volume than a 34K, while a 30K holds less.
The cup letter stays the same, but overall cup volume increases as the band size increases.
30K
34K
38K
These simplified educational diagrams show how cup volume changes as the band size increases, even when the cup letter remains K.
A bra size consists of both the band size and cup size. A 38K holds more cup volume than a 34K, while a 30K holds less, despite all three using the same cup letter.
Popular K Cup Bras (UK Sizing)
Below are selected K cup bras in UK sizing from fuller-bust specialist brands. These examples show styles commonly available in K cup sizes across a range of band sizes. If you are still confirming your size, see the fitting advice and sizing information further down this guide before purchasing.
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How to Find Your Correct K Cup Size
Measure your underband and bust carefully, then enter your measurements into our Bra Size Calculator to get a recommended UK starting size.
For measuring tips and fit checks, see our Bra Fitting Advice.
Common Fit Issues for K Cup Bras
- Band riding up at the back (often means the band is too big)
- Cups gaping or wrinkling due to shape mismatch
- Spillage at the neckline or centre of the cups
- Underwires sitting on breast tissue rather than around it
- Straps digging into the shoulders or slipping during wear
If your K cup fit feels inconsistent, try another style within the same brand or compare sizes using our Bra Size Converter.
Can I Sister Size Instead of Wearing a K Cup?
Sister sizing can be useful if your usual K cup size is unavailable in a particular bra. In general, moving up a band size requires moving down one cup size to maintain a similar cup volume, while moving down a band size requires moving up one cup size. Although sister sizes can offer a comparable volume, band tension and overall fit may feel different.
K Cup Sister Size Example
When sister sizing, the band size changes while the cup volume stays similar. A common K cup example is:
These sizes have a similar cup volume, but different band lengths.
Sister Size Comparison
30KK
32K
34JJ
These diagrams provide a simplified visual example of sister sizing. While the band size changes, the overall cup volume remains broadly similar.
Sister sizes can help when your usual size is unavailable. As the band size increases, the cup letter decreases to maintain a similar cup volume.
For a full explanation of how sister sizing works, see our Bra Sister Sizes Guide .
Use our Bra Size Converter to compare UK brand sizing and sister sizes accurately.
Explore More K Cup Guides
If you want to compare K cup sizes in more detail, these related guides can help you understand cup volume, band size, sister sizing and neighbouring cup sizes.
- How Big Are K Cups?
- J vs JJ vs K Cup Size Comparison
- K vs KK vs L Cup Size Comparison
- Bra Sister Sizes Guide
K Cup Bra FAQs
Do all brands use the same K cup sizing?
No. Different UK brands use different cup letter sequences. As a result, K cups can vary greatly in volume.
Is a UK K cup the same as a US K cup?
No. US sizing uses a different cup progression. A US K cup is smaller in volume than a UK K cup from extended UK sizing brands.
Does band size affect K cup volume?
Yes. Cup volume increases as band size increases. A 40K holds significantly more volume than a 32K.
Can K cup bras be supportive without wires?
Some non-wired options exist, but many K cup wearers prefer underwired bras for greater structure and long-term support, depending on individual needs and style choice.
K cup sits between JJ and KK in extended UK sizing. If you're deciding between sizes, it can help to compare JJ cup bras and KK cup bras to understand how cup volume increases across neighbouring sizes.
Related Cup Size Guides
For general background on bra sizing systems, see the bra size reference on Wikipedia .