D cup size: what it means, and why it is not a large cup
A D cup is four inches of difference between bust and band. It is not "a large cup": a 30D, a 34D and a 38D measure roughly 30/34, 34/38 and 38/42 in, three different bodies that all carry a D. The letter is the same in the UK, US, EU, France and Australia.
UK D: 4 in, 10.2 cm of difference
| UK | US | EU | FR | AU | JP (approx.) |
|---|---|---|---|---|---|
| 30D | 30D | 65D | 80D | 8D | E65 |
| 32D | 32D | 70D | 85D | 10D | E70 |
| 34D | 34D | 75D | 90D | 12D | E75 |
| 36D | 36D | 80D | 95D | 14D | E80 |
| 38D | 38D | 85D | 100D | 16D | E85 |
| 40D | 40D | 90D | 105D | 18D | E90 |
AU follows Berlei; Wacoal, Freya and Elomi keep UK FF and GG instead. JP is approximate because Japanese cup steps are 2.5 cm rather than one inch; our JP column stops at I. Wacoal's guide continues to JP K. "n/a" means outside this converter, not that the size does not exist. Cup-system definitions.
D cup size in inches and centimetres
A cup letter is a difference, not a volume. On a 34 band, a UK D is a 38 in (96.5 cm) bust. Every row is the band plus the cup's inches, the same arithmetic the calculator uses.
| Band | UK D bust |
|---|---|
| 30 in | 34 in (86.4 cm) |
| 32 in | 36 in (91.4 cm) |
| 34 in | 38 in (96.5 cm) |
| 36 in | 40 in (101.6 cm) |
| 38 in | 42 in (106.7 cm) |
| 40 in | 44 in (111.8 cm) |
Sister sizes keep the D cup's volume
Go down one band and up one letter, or up one band and down one letter, and the cup volume stays the same. Shown for UK D on a 34 band.
| UK | US | Compared with 34D |
|---|---|---|
| 32DD | 32DD | Tighter band, 1 letter up |
| 34D | 34D | This size |
| 36C | 36C | Looser band, 1 letter down |
The full diagonal chart, with fit fixes for a band that rides up or digs in, is on the sister sizes page.
What the +4 method does to this cup
Our +4 comparison rounds measurements to whole inches, adds 4 to an even underbust (5 to an odd one) and subtracts the padded band from the bust. Differences below 1 are labelled AA. For UK D (4 in) that changes the answer on every band.
| Underbust | Bust | Measured band (UK) | +4 method (US) |
|---|---|---|---|
| 30 in | 34 in | 30D | 34AA |
| 34 in | 38 in | 34D | 38AA |
| 38 in | 42 in | 38D | 42AA |
White and Scurr (2012) found the traditional method overestimated band size and underestimated cup size (Ergonomics 55(6)). A size from an older calculator may not be the size on this page.
D cup bras: which brand charts list one, by band
Some charts print individual sizes; others state band and cup ranges separately. Being inside both ranges does not confirm that the brand makes that combination. None of these checks confirms stock.
| Brand | UK D (4 in) |
|---|---|
| Elomi | Cup within guide range; bands 32 to 48 stated separately; combinations unconfirmed |
| Freya | Cup within guide range; bands 28 to 44 stated separately; combinations unconfirmed |
| Marks & Spencer | Chart entries: 28 to 46 |
| Victoria's Secret | International chart: 30 to 44. US guide: bands 30 to 46, cups A to O; combinations unconfirmed |
| The Little Bra Company | Cup within guide range; bands 28 to 38 stated separately; combinations unconfirmed |
| ThirdLove | Cup within guide range; bands 32 to 44 stated separately; combinations unconfirmed |
Elomi: US underband and cup sizing, 32 to 48 bands and B to O cups (UK B to K; its chart continues to UK KK). Freya: bands 28 to 44, UK cups B to K. Marks & Spencer: its UK row lists sizes from 28AA to 46K (no FF, HH or JJ); matched here by the label as printed. Victoria's Secret: US guide: bands 30 to 46, cups A to O, not every style in every size; international chart: bands 30 to 44, AA to DDD (UK E). The US ranges do not confirm every band/cup combination. The Little Bra Company: its size picker: bands 28 to 38, cups AA to D (a specialist for small sizes). ThirdLove: bands 32 to 44, AA to H in US labels, plus half cups; the ranges do not verify every combination or the UK pairing for G/H.
What is particular about the D cup
D is not automatically a large cup
The same one-inch step separates every letter on the ladder. Our 30D, 34D and 38D pages measure roughly 30/34 in, 34/38 in and 38/42 in underbust and bust: three different bodies, the same D letter, because each is exactly four inches of difference on its own band.
Is a D cup big?
Only with a band attached. A 34D holds the same cup volume as 32DD and 36C: down a band, up a letter. A 30D and a 40D share the letter and little else. We do not quote cup volumes or weights; no chart we cite gives them.
On an even underbust, the +4 comparison changes D to AA
On a 30 in underbust and 34 in bust (30D on the measured-band method), the traditional +4 method returns 34AA. On a 38 in underbust and 42 in bust (38D), it returns 42AA. Same padded-band pattern both times, the direction White and Scurr (2012) measured in UK fittings.
Marks & Spencer's US column calls it a C
On the M&S US size guide a UK 34D is a US 34C and a UK 36D is a US 36C, while a UK 32D keeps its letter (US 32D). Wacoal, Freya and Victoria's Secret print UK D as US D, and so does this site.
The last letter before the ladders split
D is the same everywhere we convert: a 34D is EU 75D, France 90D and Australia 12D. One inch up, the UK and US agree on DD but EU and French charts already print E. Two inches up, the UK says E and the US says DDD.
Quick answers
What does D cup mean?
Four inches of difference between your fullest bust and your snug underband. A 30D and a 40D carry the same letter but are different sizes; the band sets the volume.
What is a 34D in other countries?
UK and US 34D, EU 75D, France 90D and Australia 12D. Marks & Spencer's US column prints it as 34C.
What are the sister sizes of 34D?
32DD on a band one size tighter and 36C on a band one size looser. All three hold the same cup volume.
Other sizes and tools
- Bra size calculatorMeasure your size with both methods shown
- UK to US converterAny size in any of six systems
- Sister size chartThe full diagonal chart and fit fixes
- 30DSister sizes, conversions and the measurements that land on 30D
- 34DSister sizes, conversions and the measurements that land on 34D
- 38DSister sizes, conversions and the measurements that land on 38D
- A cupWhat the letter means, by band
- B cupWhat the letter means, by band
- DD cupWhat the letter means, by band
- E cupWhat the letter means, by band
- F cupWhat the letter means, by band
- G cupWhat the letter means, by band
- H cupWhat the letter means, by band
Sources
Each source was opened and checked on the date shown, or on 25 September 2026. Where sources disagree, the page says so instead of picking one silently.
- Wikipedia, "Bra size": UK and US cup ladders, the +4 method, EN 13402 and JIS cup steps
- White J, Scurr J. Evaluation of professional bra fitting criteria for bra selection and fitting in the UK. Ergonomics 2012;55(6):704-711: 45 women; the traditional method overestimated band and underestimated cup
- Marks & Spencer US, "Bras size guide": UK, AU/NZ, US/CA, EU and FR conversion table (opened 25 September 2026)
- Victoria's Secret Customer Care, "Size & Fit: International Size Chart (Outside the U.S.)": US sizes sold; bands 30 to 44, cups AA to DDD; US DDD = UK E (opened 25 September 2026)
- Freya, "International Bra Size Chart & Bra Sizing": band and cup tables in UK, EU, FR, AU/NZ, US and JP (opened 25 September 2026)
- Wacoal, "International Size Guide": UK AA to GG paired with US AA to J; AUS/NZ keeps FF and GG; band and cup rows are separate, not a stock list (opened 13 October 2026)
- Berlei Australia, size charts: AU band = underbust row, cups A to H with no FF or GG
- Victoria's Secret Customer Care, "Size & Fit: Bras & Bralettes": US guide states bands 30 to 46 and cups A to O, not all styles in all sizes; bralette rows print DD (E) and DDD (F) (opened 25 September 2026)