KK Cup Bras – Brands That Make KK Cups & How to Find Your Size
Finding well-fitting bras in a UK KK cup is extremely challenging, as very few brands manufacture cups at this level. This guide focuses specifically on KK cup bras, explaining which brands make them, how sizing works at this level, and how to confirm your correct size before buying.
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 KK cup
- Those sized out of most high-street and DD+ brands
- Customers needing maximum cup depth and support
- Shoppers comparing extended-size specialist brands
- Anyone repeatedly sister-sized due to limited availability
Why Not All KK Cup Bras Are the Same
Although KK cup is a recognised UK bra size, the cup letter alone does not represent one fixed volume. Cup volume changes with band size, which means a 30KK, 34KK and 40KK all hold different amounts of volume despite sharing the same cup letter.
The KK cup is part of the extended UK bra size sequence used by specialist fuller-bust brands. It sits between K and L, with each step representing a one-inch increase in the difference between the bust and underband measurements.
KK cup sizes are generally produced by a relatively small number of specialist lingerie brands that offer extended size ranges. Availability can vary by band size, style and retailer.
If you are comparing neighbouring cup sizes, see our K vs KK vs L Cup Size Comparison guide.
You can also explore our How Big Are KK Cups? guide to see how KK cup volume changes across different band sizes.
How Big Is a KK Cup?
A UK KK cup bra sits within the fuller-bust end of the extended UK cup size sequence. However, how large a KK cup appears depends on factors such as band size, body proportions and bra design.
For example, a 30KK and a 40KK 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 KK Cups? guide.
KK Cup Size Progression
A KK cup sits between K and L 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.
KK sits between K and L in the UK bra size sequence.
34K
34KK
34L
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 34L has more cup volume than a 34KK, while a 34K 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, KK is a separate cup size positioned between K and L. Each step represents the same one-inch increase in measurement difference, making KK one cup size larger than K and one cup size smaller than L.
The difference between brands is the lettering used, not the size step itself. For example, some traditional UK cup sequences end at lower cup sizes, while extended UK sizing includes additional sizes such as JJ, KK and L to provide more sizing options.
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 KK Cup the Same as a US KK 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 KK 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 KK cup is not one fixed volume. Cup volume increases as band size increases, so a 32KK, 38KK and 42KK are all very different in fit and capacity.
Always consider both band size and cup size together.
UK Brands That Make KK Cup Bras
- Bravissimo – Bands 28–40, cups D–L View size guide
- Elomi – Bands 32–46, cups D–LL (limited extended styles) View size guide
- Royce – Bands 28–48, cups DD–L (wire-free & specialist styles) View size guide
KK Cup Band Sizes by Brand
- Bravissimo: 32KK, 34KK, 36KK, 38KK, 40KK
- Royce: 32KK, 34KK, 36KK, 38KK, 40KK, 42KK
- Elomi: 32KK, 34KK, 36KK, 38KK, 40KK, 42KK
KK Cup Volume Changes With Band Size
Many people assume that all KK cups are the same size. In reality, cup volume increases as band size increases. A 38KK holds more volume than a 34KK, while a 30KK holds less.
The cup letter stays the same, but overall cup volume increases as the band size increases.
30KK
34KK
38KK
These simplified educational diagrams show how cup volume changes as the band size increases, even when the cup letter remains KK.
A bra size consists of both the band size and cup size. A 38KK holds more cup volume than a 34KK, while a 30KK holds less, despite all three using the same cup letter.
Popular KK Cup Bras (UK Sizing)
Below are selected KK cup bras in UK sizing from fuller-bust specialist brands. These examples show styles commonly available in KK 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 KK 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 KK 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 KK cup fit feels inconsistent, try another style within the same brand or compare brands using our Bra Size Converter.
Can I Sister Size Instead of Wearing a KK Cup?
Sister sizing can be useful if your usual KK 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.
KK Cup Sister Size Example
When sister sizing, the band size changes while the cup volume stays similar. A common KK cup example is:
These sizes have a similar cup volume, but different band lengths.
Sister Size Comparison
32L
34KK
36K
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 KK Cup Guides
If you want to compare KK cup sizes in more detail, these related guides can help you understand cup volume, band size, sister sizing and neighbouring cup sizes.
KK Cup Bra FAQs
Is KK bigger than K?
Yes. In extended UK sizing, KK is one cup step larger than K and one step smaller than L.
Do all brands offer KK cups?
No. KK cup sizes are mainly available from specialist fuller-bust brands that offer extended UK sizing ranges.
Does band size affect KK cup volume?
Yes. A 38KK holds more volume than a 32KK, even though the cup letter is the same.
KK cup sits between K and L in extended UK sizing. If you're deciding between sizes, it can help to compare K cup bras and L cup bras to understand how cup volume changes across neighbouring sizes.
Related Cup Size Guides
For background on UK bra sizing systems and cup progression, see the bra size reference on Wikipedia .