US and UK bra bands usually use the same numerical labels, but their cup progressions commonly diverge after D or DD. A UK E, F, FF, or G may have a different US letter even when the approximate cup volume is equivalent.
Direct answer
General US to UK bra size conversion
| US cup | UK cup | General relationship |
|---|---|---|
| AA | AA | Usually equivalent |
| A | A | Usually equivalent |
| B | B | Usually equivalent |
| C | C | Usually equivalent |
| D | D | Usually equivalent |
| DD | DD | Often equivalent |
| DDD or F | E | Common conversion |
| G | F | Common conversion |
| H | FF | Common conversion |
| I | G | Common conversion |
| J | GG | Common conversion |
| K | H | Common conversion |
Regional conversion visual
The Band Usually Stays the Same While the Cup Label Changes
This example shows a common conversion between US 34DDD and UK 34E.
How US Bra Sizes Work
US bra bands commonly use even numbers such as 30, 32, 34, 36, and 38.
Cup progressions are less consistent. Some brands use D, DD, DDD, G, H, and I, while others use D, DD, DDD, F, G, and H.
How UK Bra Sizes Work
UK bands commonly use the same numerical progression as US bands.
UK cup progressions frequently use D, DD, E, F, FF, G, GG, H, HH, J, and JJ.
Band
Usually the same number
A US 34 band commonly converts to a UK 34 band.
Cup
Can use different letters
The systems commonly diverge after D or DD.
Brand chart
Final source of truth
US progressions are not fully standardized.
General US and UK Band Conversion
| US band | UK band |
|---|---|
| 28 | 28 |
| 30 | 30 |
| 32 | 32 |
| 34 | 34 |
| 36 | 36 |
| 38 | 38 |
| 40 | 40 |
| 42 | 42 |
| 44 | 44 |
Where the Cup Systems Begin to Differ
AA, A, B, C, and D usually align directly. DD also commonly aligns.
After DD, UK sizing normally moves to E, while many US systems use DDD or F.
US DDD to UK Size
US DDD commonly converts to UK E.
Some US brands label the same step as F, so always check the chart.
US G to UK Size
US G commonly converts to UK F in many size charts.
US H to UK Size
US H commonly converts to UK FF.
US I to UK Size
US I commonly converts to UK G.
UK E to US Size
UK E commonly converts to US DDD or F.
UK F to US Size
UK F commonly converts to US G.
UK FF to US Size
UK FF commonly converts to US H.
UK G to US Size
UK G commonly converts to US I.
Example: US 32DDD to UK
A US 32DDD commonly converts to UK 32E.
The band remains 32 while the cup label changes.
Example: US 36H to UK
A US 36H commonly converts to UK 36FF.
Example: UK 34G to US
A UK 34G commonly converts to US 34I in many charts.
Why US Conversion Charts Differ
US bra sizing does not use one universal cup progression after D.
A brand may use DDD, F, or both, and later cup letters may shift by one or more steps.
Do Not Convert the Cup Letter Alone
Keep the band attached to the cup during conversion.
A UK 32F and a UK 38F do not represent the same cup volume.
US and UK Sister Sizes
Sister-size rules still apply within each regional progression.
Convert the regional cup correctly before moving up or down a band.
US Bra Shapes vs. UK Bra Shapes
Regional labeling does not guarantee one particular shape, but many UK brands offer extended cup ranges with varied projection and seamed construction.
Shape differences can matter more than the converted label.
Check the Product Page
Look for a size chart that identifies whether the bra uses US, UK, EU, or another system.
Do not rely only on the country where the bra is sold.
Check the Brand's Cup Sequence
Read the exact list of available cups. The sequence reveals whether the brand uses DD, DDD, E, F, FF, or another progression.
Check Band and Cup Fit After Conversion
- Fasten the bra on the loosest usable hooks.
- Check whether the band stays level.
- Place all breast tissue inside the cups.
- Check the underwires and center gore.
- Check cup edges for spilling or gaping.
- Check strap placement and movement.
Common US-to-UK Conversion Mistakes
- Assuming every cup letter matches directly
- Ignoring the brand's cup progression
- Converting the cup without the band
- Assuming US F always means the same step
- Mixing sister sizing with regional conversion
- Ignoring bra shape and wire width
- Using the retailer's country instead of the stated system
- Expecting converted sizes to fit identically across brands
Bra sizing tool
Use the Bra Size Calculator
Enter underbust and full-bust measurements to estimate a starting band, cup, regional conversion, and nearby sister sizes.
Questions and answers
Frequently Asked Questions
Are US and UK bra band sizes the same?
US and UK band labels usually use the same numbers, such as 30, 32, 34, and 36.
Are US and UK cup sizes the same?
They often match through D or DD, but the systems commonly diverge after that point.
What is US DDD in UK sizing?
US DDD or F commonly converts to UK E, although US brand labeling varies.
What is UK FF in US sizing?
UK FF commonly converts near US H in many charts.
Why do conversion charts differ?
US brands do not use one universal cup progression, so the exact retailer chart should be checked.