UK Bra Cup Size Guide | AA to LL Cup Sizes Explained
This UK Bra Cup Size Guide explains the complete UK bra cup size sequence from AA to LL, including both single-letter and double-letter cup sizes. Whether you are trying to understand bra cup progression, compare nearby cup sizes or learn how UK sizing works, this guide provides a useful starting point.
In UK bra sizing, cup letters do not work as fixed sizes on their own. A cup size must always be read together with the band size. For example, a 30F, 34F and 40F all have different cup volumes because cup capacity increases as the band size increases.
If you are unsure of your starting size, use our Bra Size Calculator, then check the result with our Bra Fitting Advice. If you shop across UK, US or EU sizing systems, use the Bra Size Converter.
- UK Bra Cup Size Sequence from AA to LL
- How UK Bra Cup Sizes Work
- Visual Bra Cup Size Examples
- UK Bra Cup Size Visual Comparison Guide
- Compare Nearby UK Cup Sizes
- UK, US and EU Cup Size Differences
- UK Bra Cup Size FAQs
In UK bra sizing, cup sizes usually progress as AA → A → B → C → D → DD → E → F → FF → G → GG → H → HH → J → JJ → K → KK → L → LL. AA is a recognised UK cup size, and double-letter cup sizes such as FF, GG and HH are full cup sizes, not half sizes.
UK Bra Cup Size Sequence from AA to LL
The UK cup-size system includes both single-letter and double-letter cup sizes. Double-letter cup sizes such as DD, FF, GG, HH, JJ and KK are full cup sizes, not half sizes.
| Cup Position | UK Cup Size | Notes |
|---|---|---|
| 1 | AA | Smallest cup size in this guide |
| 2 | A | One cup larger than AA |
| 3 | B | One cup larger than A |
| 4 | C | One cup larger than B |
| 5 | D | One cup larger than C |
| 6 | DD | One cup larger than D |
| 7 | E | One cup larger than DD |
| 8 | F | One cup larger than E |
| 9 | FF | One cup larger than F |
| 10 | G | One cup larger than FF |
| 11 | GG | One cup larger than G |
| 12 | H | One cup larger than GG |
| 13 | HH | One cup larger than H |
| 14 | J | UK sizing usually skips I |
| 15 | JJ | One cup larger than J |
| 16 | K | One cup larger than JJ |
| 17 | KK | One cup larger than K |
| 18 | L | One cup larger than KK |
| 19 | LL | Largest cup size in this guide |
How UK Bra Cup Sizes Work
Bra cup size is based on the difference between your underband measurement and your fullest bust measurement. As this difference increases, the cup letter increases.
Cup size is not a fixed volume. A 30G, 34G and 38G all have different cup volumes because cup capacity increases as band size increases.
This is why bra size always includes both a band size and a cup size. Two people wearing the same cup letter may have very different breast volumes if their band sizes differ.
Understanding this relationship is important when comparing bra sizes. A larger band size creates a larger cup volume even when the cup letter stays the same. This is why bra fitting, sister sizing and international size conversions always take both measurements into account.
If you need help finding your size, use our Bra Size Calculator, check your fit using our Bra Fitting Advice, or compare international sizing with our Bra Size Converter.
A 34G has a similar cup volume to a 32GG and a 36FF. These are known as sister sizes because the cup volume stays similar while the band size changes.
Bra Cup Size Guide: Visual UK Cup Size Comparison (AA to LL)
The visual guides below show how UK bra cup sizes progress from AA to LL using a 34 band as the reference size. This makes the cup size sequence easier to compare, while keeping in mind that cup volume changes when the band size changes.
These diagrams compare cup progression using one band size as a visual reference. A 34C, 30C and 38C are not the same cup volume, because cup volume increases as the band size increases.
Want to compare two specific UK bra sizes? Use our UK Bra Size Visual Comparison Tool to compare all 220 UK bra sizes side by side with original illustrations, measurements and sister size explanations.
Compare Nearby UK Cup Sizes
If you are between cup sizes or trying to understand nearby sizes, these comparison guides explain how neighbouring UK bra cup sizes relate to one another and how cup volume changes throughout the UK sizing sequence.
- F vs FF vs G Cup Size
- G vs GG vs H Cup Size
- H vs HH vs J Cup Size
- J vs JJ vs K Cup Size
- K vs KK vs L Cup Size
- L vs LL Cup Size
UK, US and EU Cup Size Differences
Although bra sizes may look similar across different countries, UK, US and EU sizing systems do not always use the same cup-size progression. This is particularly important in fuller-bust sizes where UK brands use double-letter cup sizes such as FF, GG, HH, JJ and KK.
Many US brands use alternative cup sequences, often including sizes such as DDD or I cups, while EU brands typically follow a different alphabetical progression. As a result, a bra labelled as the same cup letter may not always represent the same size across different sizing systems.
When shopping internationally, it is important to compare both the band size and the cup size rather than relying solely on the cup letter shown on the label. Brand-specific conversion charts can also vary, particularly in larger cup sizes.
Before ordering from an international retailer, check the brand’s own size chart and confirm whether the product uses UK, US or EU sizing. If you are comparing UK brands that use different cup progressions, use our Bra Size Converter to compare brand-specific UK cup sizes.
Although bra sizes may look similar across different countries, UK, US and EU sizing systems do not always use the same cup-size progression. This is particularly important in fuller-bust sizes where UK brands use double-letter cup sizes such as FF, GG, HH, JJ and KK. For a general overview of how different sizing systems developed, see the Wikipedia Bra Size article.
UK Bra Cup Size FAQs
UK cup sizes are based on the difference between the underband measurement and the fullest bust measurement. As this difference increases, the cup letter increases.
Yes. AA is a recognised bra cup size and is smaller than an A cup in the UK cup-size sequence.
Yes. In UK bra sizing, GG is one full cup size larger than G.
Many UK bra brands skip the letter I to avoid confusion with the number 1. The sequence usually moves from HH to J.
No. Cup volume changes with band size, so a 30G is not the same cup volume as a 38G.
There is no single largest UK bra cup size because availability varies between brands. In this guide, the UK cup-size sequence runs from AA to LL.
Understanding the UK bra cup size sequence is an important first step when finding the correct bra size. This Bra Cup Size Guide explains how cup size and band size work together, why cup volume changes across different band sizes, and how UK cup sizes progress from AA to LL.
Before ordering from an international retailer, check the brand’s own size chart and confirm whether the product uses UK, US or EU sizing. While this guide explains the UK cup-size sequence, sizing systems can vary between countries and brands. If you are comparing UK brands that use different cup progressions, use our Bra Size Converter to compare brand-specific UK cup sizes.
Find Your Starting Bra Size
To find your starting size, use our Bra Size Calculator.
You can then check your result using our Bra Fitting Advice and compare brand-specific UK cup sizes with the Bra Size Converter.