In global lingerie wholesale and procurement, bra size conversion is one of the most overlooked yet impactful aspects for buyers. Different markets utilize different bra sizing systems—for example, US bra sizing, UK bra sizing, EU bra sizing, and Asian bra sizing. Lack of knowledge among buyers can lead to the purchase of bras that don’t fit their target market, resulting in poor sales.
As a professional bra manufacturer with 20 years of experience, we provide a comprehensive analysis of the bra sizing systems in the US, UK, Europe, and Asia, and offer practical bra size conversion charts.
Bra Size Basics
Bra sizes are all based on the same basic structure: the band size and the cup size. For example, 34B, 75C, and 85D. Understanding these two components is essential for any bra size conversion.
1. Band Size
Definition: Underbust refers to the tightness of the bra’s underband, which directly affects stability and comfort.
Expression:
Centimeters (cm): Commonly used in China, Europe, and Japan, such as 70, 75, 80, 85…
Inches (inches): Commonly used in the US and UK, such as 32, 34, 36, 38…
Common Conversions:
70cm = 32inch
75cm = 34inch
80cm = 36inch
85cm = 38inch
And so on..
2. Cup Size
Definition: Cup size is determined by the difference between the bust and underbust measurements, representing the fullness of the breasts.
Common cup sizes (using the China/EU system as an example):
10cm → A cup
12.5cm → B cup
15cm → C cup
17.5cm → D cup
20cm → E cup
22.5cm → F cup
3. Example
If a person’s underbust is 75cm and their upper bust is 90cm, with a difference of 15cm, the corresponding size would be 75C.
US size system
1. Band Size
US bra sizes measure the underbust circumference in inches.
Commonly used under the size: 28, 30, 32, 34, 36, 38, 40, 42, 44 and so on.
2. Cup Size
Cup Size: the difference between the upper bust minus the lower bust.
US cup size sequence: AA-A-B-C-D-DD (or E)-DDD (or F)-G-H-I-K…
3. Calculation: Upper bust – lower bust = difference (inches)
0–0.5 inches → AA
0.5–1 inch → A
1–2 inches → B
2–3 inches → C
3–4 inches → D
4–5 inches → DD/E
5–6 inches → DDD/F
6–7 inches → G
7–8 inches → H
8–9 inches → I
9–10 inches → J
UK Sizing System
1. Underbust:
Same as US, in inches
Commonly 28, 30, 32, 34, 36, 38, 40, 42…
2. Cups:
The UK cup alphabetical system is one of the most subdivided, as it adopts the ‘single letter + double letter’ alternation.
The cup order is as follows:
AA – A – B – C – D – DD – E – F – FF – G – GG – H – HH – J – JJ – K – KK – L …
Note: DD is a separate cup, not E as in the US.
The cup distinction is much finer and is especially friendly to plus sizes and fuller busts.
3. Calculation:
The cup size is still determined by the difference (in inches) between the upper bust – lower bust.
<1 inch → AA
1 inch → A
2 inches → B
3 inches → C
4 inches → D
5 inches → DD
6 inches → E
7 inches → F
8 inches → FF
9 inches → G
10 inches → GG
11 inches → H
And so on…
Similarities and differences between US and UK sizes:
Similarities:
1. Same structure
Both bra sizes are made up of underwire + cup.
The underwire is measured in inches.
2. Measurements are the same.
The underwire determines the underwire size.
The difference between the upper bust minus the lower bust determines the cup size.
3. The small cups are basically the same.
AA, A, B, C, D mean the same thing in both UK and US because the difference is very small.
For example: UK 34C ≈ US 34C.
Differences：
1. Cup naming rules are different
US: AA – A – B – C – D – DD/E – DDD/F – G – H – I – J…
(DD, DDD after D, some brands write E, F instead)
UK: AA – A – B – C – D – DD – E – F – FF – G – GG – H – HH – J – JJ – K – KK…
(double letters after D for more precise breakdown)
European size system
1. Underbust
European underbusts are measured in centimeters (cm). They are expressed in multiples of 5. Common underbust sizes include: 65, 70, 75, 80, 85, 90, 95, 100, etc.
For example:
Underbust 68–72 cm → EU 70
Underbust 73–77 cm → EU 75
Corresponding Relationship (with US/UK):
EU 70 ≈ US/UK 32
EU 75 ≈ US/UK 34
EU 80 ≈ US/UK 36
EU 85 ≈ US/UK 38
EU 90 ≈ US/UK 40
EU 95 ≈ US/UK 42
EU 100 ≈ US/UK 44
2. Cup Size
European cup sizes are represented by single letters: A, B, C, D, E, F, G, H, I, J…
For every 2cm difference between underbust and underbust, increase your cup size by one;
12–14 cm → A
14–16 cm → B
16–18 cm → C
18–20 cm → D
20–22 cm → E
22–24 cm → F
24–26 cm → G
26–28 cm → H
And so on…
Example:
Suppose a woman has an underbust of 75 cm and a bust of 93 cm:
Upper bust minus underbust = 18 cm → corresponds to a EU C cup size
So, EU size = 75C
Asian size system
1. Underbust
Asian underbusts are also expressed in centimeters (cm). Common underbust sizes: 65, 70, 75, 80, 85, 90, 95, 100…
Conversions:
Asia 70 ≈ EU 70 ≈ UK/US 32
Asia 75 ≈ EU 75 ≈ UK/US 34
Asia 80 ≈ EU 80 ≈ UK/US 36
Asia 85 ≈ EU 85 ≈ UK/US 38
2. Cup Size
Asia cup sizes are similar to those in Europe (EU), also using single letters: A, B, C, D, E, F, G, H…
Determination: Upper bust – lower bust difference (cm).
For every 2.5cm increase, the cup size increases by one letter (this is slightly different from the EU, which changes letters every 2cm).
10 cm → A
12.5 cm → B
15 cm → C
17.5 cm → D
20 cm → E
22.5 cm → F
25 cm → G
27.5 cm → H
And so on…
Similarities and Differences between European and Asian Sizing
Similarities:
1. Underbust measurements are measured in the same unit.
Both are measured in centimeters.
2. Cup sizes are marked with letters.
Both sizes are marked with single letters (A, B, C, D, E, F, G, etc.).
Differences:
1. Cup size differences vary.
Europe changes letters every 2 cm, while Asia changes letters every 2.5 cm. Therefore, Asian cup sizes tend to be smaller.
For example: EU 85B ≠ Asia 85B
EU B → Bust is approximately 14–16 cm larger than Underbust
Asia B → Bust is approximately 12.5–15 cm larger than Underbust
So, for both sizes marked as a B cup:
The EU 85B has a slightly larger cup size than the Asia 85B. Asian sizes are generally about half a cup smaller, and the difference is more noticeable in larger cup sizes.
Bra Size Conversion Charts
