Sizing decoded May 30, 2026 3 min read
What Does DDD Mean in Bra Sizing?
DDD = US triple-D cup = F in UK/EU. 6-inch difference between bust and underbust.
The Decoder
DDD = 6 inches
DDD is the US triple-D cup. Bust − underbust = 6 inches. Equivalent to F cup in UK/EU.
US Cups to International Equivalents
| US | UK/EU | Bust − underbust |
|---|---|---|
| A | A | 1" |
| B | B | 2" |
| C | C | 3" |
| D | D | 4" |
| DD | DD/E | 5" |
| DDD | F | 6" |
| DDDD | FF/G | 7" |
| — | G | 7-8" |
| — | H | 8" |
FAQs
What does DDD mean?
US triple-D. 6-inch bust-to-underbust difference. = F in UK/EU.
DDD = F?
Yes — same cup, different notation.
Bigger than DDD?
DDDD (G in UK), H, I, J, K.
Underwire for DDD?
Almost always yes — needs structural support.
Get the Right Cup
For full bra reference see bra size chart; 32A/34B/36C decoded; sister sizes.
Selling DDD+ bras on Shopify?
Tailor Size Guide adds US/UK/EU bra-cup conversion to every listing.