Bra Size Converter
A 34C in the US is not a 34C in the UK, and the French label the same bra as 85C while Italy calls it 3C. This converter translates bra sizes across the six major regional systems (US, UK, EU, FR/BE/ES, AU/NZ, JP), handles the cup-letter quirks (there is no UK “DD” that equals US “DD”), and suggests sister sizes when you need to scale band up or down without changing cup volume.
How bra size conversion works
-
1
Pick your starting region
Enter the size on the label of a bra that currently fits you — US 34D, UK 32DD, EU 70E, whatever your local system.
-
2
Tool separates band and cup
Band is the underbust measurement; cup is the difference between bust and underbust. Regions encode both differently.
-
3
Conversion table maps across systems
Every target region shows the equivalent band number and cup letter using the standard conversion table.
-
4
Sister sizes appear
If the exact band is unavailable in a brand, sister sizes (band up / cup down and band down / cup up) preserve the same cup volume.
Band size conversion
| UK / US (in) | EU / DE | FR / BE / ES | JP |
|---|---|---|---|
| 28 | 60 | 75 | 60 |
| 30 | 65 | 80 | 65 |
| 32 | 70 | 85 | 70 |
| 34 | 75 | 90 | 75 |
| 36 | 80 | 95 | 80 |
| 38 | 85 | 100 | 85 |
| 40 | 90 | 105 | 90 |
Cup size conversion (selected)
| UK | US | EU / DE / FR / BE / ES / JP |
|---|---|---|
| A | A | A |
| B | B | B |
| C | C | C |
| D | D | D |
| DD | DD / E | E |
| E | DDD / F | F |
| F | G | G |
| FF | H | H |
| G | I | I |
| GG | J | J |
Note the UK-US cup divergence from DD onward — UK goes DD, E, F, FF, G… while US commonly writes DD, DDD, G, H.
Sister sizes
Cup volume depends on the difference between bust and band. Sizes that share cup volume form a “sister” chain:
- 30D → 32C → 34B (same cup volume, looser band each step up)
- 34C → 32D → 30DD (same cup volume, tighter band each step down)
If your favourite brand is out of your exact size, sister sizes preserve the cup while adjusting band.
Fit check
- Band should sit horizontal across your back, not ride up.
- Underwire should encircle the full breast tissue without cutting into it.
- Straps should support without digging in — if they cause most of the lift, the band is too loose.
- Cup gaping means cup too large; spillover means cup too small.
Frequently Asked Questions
The cup-letter sequence diverges from DD onward. US uses DD, DDD, G, H, … while UK uses DD, E, F, FF, G. A UK 34DD is closer to a US 34E; a UK 34G is about a US 34H.
Underbust (snug tape just under the breasts) gives band. Overbust (loose tape at the fullest point) minus underbust gives cup (1 inch = A, 2 = B, 3 = C, etc.). Always re-measure if weight changes or between major life stages.
Try sister sizes. Band runs tight at first; if your band rides up, go down one band and up one cup. If it digs in, go up one band and down one cup.
The EU/DE/UK imports usually match the table, but French/Belgian/Spanish brands add 15 to the band number (EU 70 = FR 85). Italian brands sometimes use 0-8 cup codes instead of letters — those need a separate lookup.
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