Brassiere sizes are commonly labeled by manufacturers with a code consisting of a number and one or more Latin capital letters, the number referring to the circumference of the ribcage, and the letter referring to the relative volume of the breasts. The single most confusing this about bras is that cup sizes are relative. Most people think that cup sizes are the same across all bra sizes, meaning that a B cup on a 34 is the same size as on a 36. This is not true. Cup sizes are relative to the band size, so the same cup size is bigger on a bigger band size. Try this experiment - compare a 32DD and a 36DD. The cup on the 32DD is much smaller than the cup on the 36DD - in fact, it holds about the same volume as a 36C. So don't presume your cup size will always be the same - it might adjust with your band size. Several different systems are used worldwide to define these labels, based on either inch or centimetre body measurements.
|Difference between bust size |
and underbust size (inches)
(UK and Australia)
| Cup size |
(rest of Europe, Canada and US)
|Less than one inch||AA||AA|
|5 inches||DD||E or DD|
|6 inches||E||F or DDD|
The actual volume of the bra cup depends not only on the cup size calculated as above, but also increases with the band size. In fact, most bra manufacturers use the same cup volume for bras which are related by an increase in cup size and a decrease in band size. For instance, the cup volume is the same for 30D, 32C, 34B, 36A, etc. It is for this reason that bra sizes have "sister sizes" which are related in this way by having the same cup volume. Although it is important that a wearer has a correctly fitting bra, it is sometimes possible that two adjacent sister sizes fit equally well, since the cups are the same size, and the difference in band size can be accommodated by fastening the back strap on a different hook.
The European dress-size standard EN 13402 defines bra sizes based on the following two body dimensions (measured in centimetres): bust girth : maximum horizontal girth measured during normal breathing with the subject standing erect and the tape-measure passed horizontally, under the armpits (axillae), and across the bust prominence (preferably measured with moderate tension over a brassiere that shall not deform the breast in an unnatural way and shall not displace its volume) underbust girth : horizontal girth of the body measured just below the breasts
Bras are labeled with the underbust girth (rounded to the nearest multiple of 5 cm), followed by a letter code that indicates the
|Cup size [cm]||10–12||12–14||14–16||16–18||18–20||20–22||22–24||24–26|
Example: A woman with underbust girth 89 cm and bust girth 108 cm has cup size 19 cm (= 108 cm – 89 cm) or "D". Her underbust girth rounded to the nearest multiple of 5 cm is 90 cm. Therefore, her bra size according to the new standard is 90D.
The EN 13402 standard is (as of 2006) still relatively new, and a range of other cup-size definitions are also currently used by European vendors, using either centimeters or inches to indicate the underbust girth.
One common cup size system amongst European manufacturers, in order of increasing size, is: AAA-AA-A-B-C-D-DD-E-F-FF-G-GG-H-J, although the use of double letters is not consistent between manufacturers (e.g. some may use EE rather than F, DDD rather than E, etc.). The majority of bra bands run true to size (as in, a size 36 band measures, when stretched, 36 inches). It is expected that the EN 13402 standard will eventually help resolve the current confusion surrounding cup-size codes in Europe.
|EU and Japan||60–65||65–70||70–75||75–80||80–85||85–90||90–95||95–100||100–105||105–110||110–115||115–120|
|USA and UK||30||32||34||36||38||40||42||44||46||48||50||52|
|France and Spain||75–80||80–85||85–90||90–95||95–100||100–105||105–110||110–115||115–120||120–125||125–130||130–135|
The most common bra size worn in the UK is 36C. However, many studies have shown that around 80% of women are wearing the wrong size with the most common mistake being to select a bra with too large a back band and too small a cup, for example, 38C instead of 34E, or 34B instead of 30D. Bravissimo, the large cup size specialist, estimates that the average woman should be wearing a 34DD or 34E bra. These fitting problems are exacerbated by the lack of education about bra sizing and fitting, and the myths perpetrated by the media (DD cup breasts are regarded as being significantly larger than average.)