Why do cup sizes vary between UK bra brands?

All UK bra sizing follows the same 1-inch rule, but brands use different cup letter sequences. This means the same cup letter can represent different volumes depending on the brand.

Does band size affect cup volume?

Yes. Cup volume increases as band size increases, so a 38 cup holds more volume than the same cup letter on a smaller band.

Is UK bra sizing the same as US or EU sizing?

No. UK, US and EU sizing systems use different cup progressions. Always use a conversion chart when comparing sizes across regions.

Bra Size Guides

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, not all K cups represent the same volume. This is because different UK cup letter sequences are used by different brands, even though the underlying sizing rule is the same.

Bra cup sizes are based on a simple fitting rule: each step in the UK cup sequence represents a 1 inch difference between the underband and the fullest bust measurement.

Traditional UK brands, including Triumph, follow a shorter cup sequence: B, C, D, DD, E, F, G, H, J, K.

Fuller-bust specialist brands use an extended UK cup sequence that includes additional double letters: D, DD, E, F, FF, G, GG, H, HH, J, JJ, K, KK, L, LL.

Each step in both systems represents the same 1 inch increase in cup depth. The difference between brands is not how the size is measured, but how those 1-inch steps are labelled.

As a result, a traditional-sequence K cup has the same cup volume as an extended-sequence H cup. An extended-sequence K cup is four full cup sizes larger than a traditional-sequence K cup.

This difference is not related to support, quality or construction. It is simply the result of using different cup letter progressions. Both systems are valid UK sizing methods, but they are not interchangeable by letter alone at higher cup sizes.

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.

How Cup Sizes Are Actually Measured

All UK bra sizing follows the 1-inch rule, meaning each step in the cup sequence represents a 1-inch increase in the difference between the underband and the fullest bust measurement. This grading system is used consistently across all UK brands.

Differences arise because some brands use a traditional UK cup letter sequence, while others use an extended UK sequence that includes additional double-letter cups. The difference is in how cup sizes are named, not how they are measured.

For example, a traditional-sequence K cup has the same cup volume as an extended-sequence H cup. An extended-sequence K cup is four full cup sizes larger than a traditional-sequence K cup.

This does not reflect a difference in quality or support. It is simply the result of using different cup letter progressions. Always compare sizes using measurements and conversion charts rather than relying on the cup letter alone.

Important: A K cup is not one fixed size.
Cup volume increases as the band size increases, so a 30K, 36K and 44K are all very different in fit and capacity.
Always consider both band size and cup size together when choosing brands or 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, 44K 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

How to Find Your Correct K Cup Size

Measure your underband and bust, then enter your measurements into our Bra Size Calculator. For detailed measuring and fit checks, visit our Bra Fitting Advice.

Common Fit Issues for K Cup Bras

Cups cutting in or spilling
Underwires sitting on breast tissue
Straps taking too much weight
Bands riding up
Loss of support throughout the day

Can I Sister Size Instead of Wearing a K Cup?

Sister sizing is rarely a good long-term solution at K cup level. Moving up a band and down a cup usually reduces support and stability. If you are repeatedly sister sizing, it typically means the brand or cup sequence is wrong for your bust.

Use our Bra Size Converter to compare UK brands accurately.

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.

Related Cup Size Guides

For a general overview of bra sizing systems and measurement principles, you can also refer to the bra size reference on Wikipedia . This provides background context on different sizing systems alongside specialist brand guidance.