Bra sizing has two independent dimensions: band size (the measurement around the ribcage below the bust) and cup size (the difference between bust and band measurements). The same bra size — for example, 34B — means something different in every country because band and cup scales are defined differently in each region.
How it works
Measure 1: Band measurement
Wrap a tape measure snugly around your ribcage, directly below the bust.
Round to the nearest even number in inches (US/UK) or nearest cm (EU).
Measure 2: Bust measurement
Measure loosely around the fullest part of the bust.
Cup size = bust measurement − band measurement
US/UK cup scale (per inch of difference):
AA < 1 in | A = 1 in | B = 2 in | C = 3 in | D = 4 in
DD/E = 5 in | F/DDD = 6 in | G = 7 in | H = 8 in
EU cup scale (per cm of difference):
AA < 10 cm | A = 10–12 cm | B = 12–14 cm | C = 14–16 cm | D = 16–18 cm
E = 18–20 cm | F = 20–22 cm | G = 22–24 cm | H = 24–26 cm
Important: Cup size is not absolute — it is relative to band size. A 34C and a 36B have the same cup volume (called "sister sizing"). Moving up one band size requires moving down one cup letter to maintain the same fit.
Practical examples
Example 1 — UK 34B to EU. Band 34 UK → EU band 75. Cup B UK → Cup B EU. EU size: 75B.
Example 2 — EU 80D to US. Band 80 EU → US band 36. Cup D EU → Cup D US. US size: 36D.
Example 3 — French sizing. French (and Spanish, Belgian, Italian) sizing adds 15 to the EU band: EU 70 = FR 85, EU 75 = FR 90, EU 80 = FR 95. Cup letters are the same as EU. A US 34B → EU 75B → FR 90B.
Common mistakes
- Using UK DD and US DD interchangeably. In the UK, DD is one cup above D. In the US, DD is typically equivalent to E and is one size above D. Above D, the UK and US cup systems diverge further — UK cups continue F, FF, G, GG, H, HH, J; US cups use DDD, F, G, H. Always check which system is used.
- Confusing French/EU sizing. French sizing adds 15 to the EU band number. A bra marked "85B" in a French store is EU 70B (UK/US 32B), not EU 85B.
- Treating cup letters as fixed. Cup letters are relative. A 36C has the same cup volume as a 34D — they are sister sizes. If a cup is too full but the band fits, go up one band and down one cup.
- Measuring over padding. Measure your bust and band in a non-padded bra or no bra. Padded bras inflate the bust measurement.
- Not re-measuring after significant weight change. Band and cup measurements both change with body weight. Re-measure if your weight changes by more than 10 lbs / 5 kg.
International and regional variations
Band sizes
| UK / US (in) | EU (cm) | FR / ES / BE / IT | AU / NZ |
|---|---|---|---|
| 28 | 60 | 75 | 6 |
| 30 | 65 | 80 | 8 |
| 32 | 70 | 85 | 10 |
| 34 | 75 | 90 | 12 |
| 36 | 80 | 95 | 14 |
| 38 | 85 | 100 | 16 |
| 40 | 90 | 105 | 18 |
| 42 | 95 | 110 | 20 |
| 44 | 100 | 115 | 22 |
| 46 | 105 | 120 | 24 |
Cup sizes
| UK | US | EU / FR / ES | AU / NZ |
|---|---|---|---|
| AA | AA | AA | AA |
| A | A | A | A |
| B | B | B | B |
| C | C | C | C |
| D | D | D | D |
| DD | DD / E | E | DD |
| E | DDD / F | F | E |
| F | F / G | G | F |
| FF | G / H | H | FF |
| G | H / I | I | G |
| GG | I / J | J | GG |
| H | J / K | K | H |
Note: Cup letter equivalence above D diverges between countries. The table above shows the most common mapping, but individual brands and manufacturers may vary.