Brassiere measurement (also called brassiere size, bra size or bust size) refers to determining what size of bra a woman wears and mass-producing bras that will fit most women. Bra sizes usually consist of a number, indicating a band size around the woman's torso, and one or more letters indicating the breast cup size. Bra cup sizes were invented in 1932 and band sizes became popular in the 1940s.
Bra sizes vary from one manufacturer to another, and from country to country. Women's bodies and breasts may not conform to the sizes offered by companies. As a result, some women have a difficult time finding a properly fitted bra. Up to 80% of women wear the wrong size bra, causing 40% to 60% to experience pain of one kind or another.
Bra sizing systems are typically used to label off-the-shelf bras and are not used for custom-made bras or bras built into other garments. Bra size labeling systems vary from country to country, while manufacturers do not adhere to international standards. Some manufacturers have been found to deliberately mis-state the band size. One study found that the label size was consistently different from the measured size. Furthermore, the shape, size, symmetry, and spacing of women's breasts vary considerably, and can differ greatly from the standard off-the-shelf bra shapes and sizes, especially if the breasts have been augmented, are tubular shaped, or if they sag.
- 1 Measurement method origins
- 2 Correct fitting
- 3 Measurement difficulties
- 4 Measurement methods
- 5 Research
- 6 Advertising and retail influence
- 7 International fitting standards
- 8 Calculating cup volume and breast weight
- 9 See also
- 10 References
- 11 Further reading
Measurement method origins
Parisienne Madaleine Gabeau received a United States patent on 21 November 1911 for a brassiere with soft cups and a metal band that supported and separated the breasts. To avoid the prevailing fashion that created a single "monobosom", her design provided "that the edges of the material d may be carried close along the inner and under contours of the breasts, so as to preserve their form, I employ an outlining band of metal b which is bent to conform to the lower curves of the breast."
Cup design origins
In October 1932, the S.H. Camp and Company were the first to measure cup size by the letters of the alphabet, A, B, C, and D, though the letters represented how pendulous the breasts were and not their volume. Camp's advertising in the February 1933 issue of Corset and Underwear Review featured letter-labeled profiles of breasts. Cup sizes A through D were not intended to be used for larger-breasted women.
In 1937, Warner added four cup sizes (A, B, C and D) to its product descriptions. Two other companies, Model and Fay-Miss (renamed in 1935 as the Bali Brassiere Company) followed, offering A, B, C and D cup sizes in the late 1930s. Catalog companies continued to use the designations Small, Medium and Large through the 1940s.:101 Britain did not adopt the American cups in 1933, but resisted using cup sizes for its products until 1948. The Sears Company finally applied cup sizes to bras in its catalog in the 1950s.:102
Band measurement origins
Adjustable bands were introduced using multiple hook and eye closures in the 1930s. Prior to the widespread use of bras, the undergarment of choice for Western women was a corset. To help women meet the perceived ideal female body shape, corset and girdle manufacturers used a calculation called hip spring, the difference between waist and hip measurement (usually 10-12 inches).
The band measurement system was created by U.S.A. bra manufacturers just after World War II.
The underwire was first added to a strapless bra in 1937 by André, a custom-bra firm. Patents for underwire-type devices in bras were issued in 1931 and 1932, but were not widely adopted by manufacturers until after World War II when metal shortages eased.
In the 1930s, Dunlop chemists were able to reliably transform rubber latex into elastic thread. After 1940, "whirlpool," or concentric stitching was used to shape the cup structure of some designs. The man-made fibres were quickly adopted by the industry because of their easy-care properties. Since a brassiere must be laundered frequently, easy-care fabric was in great demand.
Pendulous breasts can make it difficult for a woman to properly fit a bra. For best results, the breasts should be measured twice: once when standing upright, once bending over at the waist with the breasts hanging down. If the difference between these two measurements is more than 10 cm, choose the number halfway between them as a starting point for calculating the cup size. The results of a number of reports, surveys and studies in different countries show that between 80% to 85% of women wear incorrectly fitted bras. In November 2005, Oprah Winfrey produced a show devoted to bras and bra sizes, during which she revealed research that eight out of ten women wear the wrong size bra.
Larger breasts and bra fit
When purchasing bras, larger-breasted women usually have difficulty selecting a well-fitting bra. Buxom women are more likely than smaller-breasted women to wear an incorrectly sized bra. They tend to buy bras that are too small, while smaller-breasted women tend to purchase bras that are too large. Studies have revealed that the most common mistake made by women when selecting a bra was to choose too large a back band and too small a cup, for example, 38C instead of 34E, or 34B instead of 30D.
As breasts become larger, their shape and the distribution of tissue within them changes. The breasts may become ptotic. This makes measurements increasingly unreliable. The heavier a woman's build, the more difficult it is to obtain accurate measurements, as measuring tape sinks into the flesh more easily.
In a study conducted in the United Kingdom of 103 women seeking mammoplasty, researchers found a strong link between obesity and inaccurate back measurement. They concluded that "obesity, breast hypertrophy, fashion and bra-fitting practices combine to make those women who most need supportive bras the least likely to get accurately fitted bras."
One issue that complicates finding a correctly fitting bra is that band and cup sizes are not standardized, but vary considerably from one manufacturer to another, resulting in sizes that only provide an approximate fit. Women cannot rely on labeled bra sizes to identify a bra that fits properly. Scientific studies show that the current system of bra sizing may be inaccurate.
Manufacturers cut their bras differently, so, for example, two 34B bras from two companies may not fit the same woman. Customers should pay attention to which sizing system is used by the manufacturer. The main difference is in how cup sizes increase, by 2 cm or 1 inch (= 2.54 cm, see below). Some French manufacturers also increase cup sizes by 3 cm. Unlike dress sizes, manufacturers do not agree on a single standard.
British bras currently range from A to LL cup size (with Rigby&Peller recently introducing bras by Elila which go up to US-N-Cup), while most Americans can find bras with cup sizes ranging from A to G. Some brands (Goddess, Elila) go as high as N, a size roughly equal to a British JJ-Cup. In continental Europe, Milena Lingerie from Poland produces up to cup R. Larger sizes are usually harder to find in retail outlets. As the cup size increases, the labeled cup size of different manufacturers' bras tend to vary more widely in actual volume. One study found that the label size was consistently different from the measured size.
Even medical studies have attested to the difficulty of getting a correct fit. Research by plastic surgeons has suggested that bra size is imprecise because breast volume is not calculated accurately:
The current popular system of determining bra size is inaccurate so often as to be useless. Add to this the many different styles of bras and the lack of standardization between brands, and one can see why finding a comfortable, well-fitting bra is more a matter of educated guesswork, trial, and error than of precise measurements.
The use of the cup sizing and band measurement systems has evolved over time and continues to change. Experts recommend that women get fitted by an experienced person at a retailer offering the widest possible selection of bra sizes and brands.
Bad bra-fit symptoms
If the straps dig into the woman's shoulder, leaving red marks or causing shoulder or neck pain, the bra band is not offering enough support. If breast tissue overflows the bottom of the bra, under the armpit, or over the top edge of the bra cup, the cup size is too small. Loose fabric in the bra cup indicates the cup size is too big. If the underwires poke the breast under the armpit or if the bra's center panel does not lie flat against the woman's sternum, the cup size is too small. If the band rides up in woman's torso in the back, the band size is too big. If it digs into the flesh, causing the flesh to spill over the edges of the band, the band is too small. If the band feels tight this may be due to the cups being too small, instead of going up in band size a woman should try going up in cup size. Similarly a band might feel too loose if the cup is too big. A woman can test whether a bra band is too tight or too loose by reversing the bra on her torso so that the cups are in the back and then check for fit and comfort. Generally, if a woman has to continually adjust her bra or experiences general discomfort, the bra is a poor fit and the woman should get a new fitting.
Obtaining best fit
Bra experts recommend that women, especially those whose cup sizes are D or larger, get a professional bra fitting from the lingerie department of a clothing store or a specialty lingerie store. However, even professional bra fitters in different countries including New Zealand and the United Kingdom produce inconsistent measurements of the same woman.
A 2004 study by Consumers Reports in New Zealand found that 80% of department store bra fittings resulted in a poor fit. However, because manufacturer's standards widely vary, women cannot rely on their own measurements to obtain a satisfactory fit. Some bra manufacturers and distributors state that trying on and learning to recognize a properly fitting bra is the best way to determine a correct bra size, much like shoes.
Bra fitters generally agree that a correctly fitting bra should meet the following criteria:
- When viewed from the side, the edge of the chest band should be horizontal, should not ride up the back, and should be firm but comfortable.
- Each cup's underwire at the front should lie flat against the sternum (not the breast), along the inframammary fold, and should not dig into the chest or the breasts, rub or poke out at the front.
- The breasts should be enclosed by the cups and there should be a smooth line where the fabric at the top of the cup ends.
- The apex of the breast, the nipple, must be in the center of the cup.
- The breast should not bulge over the top or out the sides of the cups, even with a low-cut style such as the balconette bra.
- The straps of a correctly fitted bra should not dig into or slip off the shoulder, which suggests a too-large band.
- The back of the bra should not ride up and the chest band should remain parallel to the floor when viewed from the back.
- The breasts should be supported primarily by the band around the rib cage, rather than by the shoulder straps.
- The woman should be able to breathe and move easily without the bra slipping around.
Confirming bra fit
One method to confirm that the bra is the best fit has been nicknamed the Swoop and Scoop. After identifying a well-fitting bra, the woman bends forward (the swoop), allowing her breasts to fall into the bra, filling the cup naturally, and then fastening the bra on its loosest hook. When she stands up, she uses the opposite hand to place each breast gently into the cup (the scoop). She then runs her index finger along the inside top edge of the bra cup to make sure breast tissue doesn't spill over the edges.
Constructing a properly fitting brassiere is difficult. Adelle Kirk, formerly a manager at the global Kurt Salmon management consulting firm that specializes in the apparel and retail businesses, said that making bras is complex.
Bras are one of the most complex pieces of apparel. There are lots of different styles, and each style has a dozen different sizes, and within that there are a lot of colors. Furthermore, there is a lot of product engineering. You've got hooks, you've got straps, there are usually two parts to every cup, and each requires a heavy amount of sewing. It is very component intensive.
Asymmetrical breasts common
Obtaining the correct size is complicated by the fact that up to 90 percent of women's breasts are asymmetrical to some degree, in which case it is recommended that they wear a bra fitted to the larger breast and pad the smaller or shorten its strap to avoid gapping. Up to 25% of women's breasts display a persistent, visible breast asymmetry, which is defined as differing in size by at least one cup size. For about 5% to 10% women, their breasts are severely different, with the left breast being larger in 62% of cases. This is thought to be a result of right handed muscle usage and the favoritism of that arm not allowing as much fatty tissue to accumulate.
Manufacturer Fruit of the Loom attempted to solve the problem of finding a well-fitting bra for asymmetrical breasts by introducing Pick Your Perfect Bra, which allow women to choose a bra with two different cup sizes, although it is only available in A through D cup sizes.
Breast volume variation
Obtaining the correct size is further complicated by the fact that the size and shape of a woman's breasts change during her menstrual cycle and can experience unusual or unexpectedly rapid growth in size due to pregnancy, weight gain or loss, or medical conditions. Even breathing can substantially alter the measurements.
Some women's breasts can change shape by as much as 20% per month.
"Breasts change shape quite consistently on a month-to-month basis, but they will individually change their volume by a different amount ... Some girls will change less than 10% and other girls can change by as much as 20%." Would it be better not to wear a bra at all then? "... In fact there are very few advantages in wearing existing bras. Having a bra that's generally supportive would have significant improvement particularly in terms of stopping them going south ... The skin is what gives the breasts their support"
Increasing breast size
In 2010, the most common bra size sold in the UK was 36D. In 2004, market research company Mintel reported that bust sizes in the United Kingdom had increased from 1998 to 2004 in younger as well as older consumers and that the shift was not limited to overweight women. while a more recent study showed that the most often sold bra size in the US in 2008 was 36D.
Bra retailers recommend several methods for measuring a woman's band and cup size. These are based on two primary methods, either under the bust or over the bust, and sometimes both. Calculating the correct bra band size is complicated by a variety of factors. The American National Standards Institute states that while a voluntary consensus of sizes exists, there is much confusion to the ‘true’ size of clothing. As a result, bra measurement can be considered an art and a science. Online shopping and in-person bra shopping experiences may differ because online recommendations are based on averages and in-person shopping can be completely personalized so the shopper may easily try on band sizes above and below her between measured band size. For the woman with a large cup size and a between band size, she may find her cup size is not available in local stores so may have to shop online where most large cup sizes are readily available on certain sites. Others recommend rounding to the nearest whole number.
Band measurement methods
There are several possible methods for measuring a woman's bust.
A measuring tape is pulled around the woman's torso at the inframammary fold. The tape is then pulled tight while remaining horizontal and parallel to the floor. The measurement in inches is then rounded to the nearest even number for the band size.
This method begins the same way as the underbust +0 method, where a measuring tape is pulled tight around the woman's torso under the bust while remaining horizontal. If the measurement is even, 4 is added to calculate the band size. If it is odd, 5 is added. Kohl’s uses this method for its online fitting guide.
Currently, many large U.S. department stores determine band size by starting with the measurement taken underneath her bust similar to the aforementioned underbust +0 and underbust +4 methods. A sizing chart or calculator then uses this measurement to determine the band size. Band sizes calculated using this method vary between manufacturers, although the band sizes generally lie in between band sizes that would result from the underbust +0 method and underbust+4 method.
Above the breasts
Victoria's Secret uses this method, where a measuring tape is pulled around the woman's torso under the armpit and above the bust. Because band sizes are most commonly manufactured in even numbers, the wearer must round to the closest even number.
Cup measurement methods
Women can calculate their cup size by calculating the difference between their bust size and their band size. The bust size, bust line measure, or over-bust measure is the measurement around the women's torso over the fullest part of the breasts, with the crest of the breast halfway between the elbow and shoulder, usually over the nipples, ideally while standing straight with arms to the side and wearing a properly fitted bra. This practice assumes the woman's current bra fits her correctly. The measurements are made in the same units as the band size, either inches or centimetres. The cup size is calculated by subtracting the band size from the over-the-bust measurement.
Cup sizes vary
Cup sizes vary from one country to another. The larger the cup size, the bigger the variation.
Surveys of bra sizes tend to be very dependent on the population studied and how it was obtained. For instance, one U.S. study reported that the most common size was 34B, followed by 34C, that 63% were size 34 and 39% cup size B. However, the survey sample was drawn from 103 Caucasian student volunteers at a Midwest U.S. university aged 18–25, and excluded pregnant and nursing women.
Bra maker Triumph conducted a survey in 2007 to determine the percentage of women wearing four cup sizes, and found that 57% of British women, more than any other country, need a D cup.
Measuring cup size without a bra
Women who have difficulty calculating a correct cup size may be able to find a correct fit using a method adopted by plastic surgeons. Using a flexible tape measure, position the tape at the outside of the chest, under the arm, where the breast tissue begins. Measure across the fullest part of the breast, usually across the nipple, to where the breast tissue stops at the breast bone. This measuring approach assumes that the woman's breasts are not so large or pendulous that they sag significantly, making measuring across the fullness of the breast impractical. Only women whose breasts are firm and spherical can measure without a bra.
Conversion of the measurement to cup size is as follows:
These cup measurements are only correct for a 34-inch band because cup size is relative to band size. The volume of a brassiere cup is the same for 30D, 32C, 34B, and 36A, though the shape of each cup may be different. These related bra sizes of the same cup volume are called sister sizes. It is sometimes possible that two adjacent sister sizes will both fit a woman, since the cup volume is the same, while the band size can be adjusted to a small degree by using the hook and eye fasteners in the bra clasp.
English mechanical engineer and professor John Tyrer from Loughborough University tackled the problem of bra design after his wife returned disheartened from a shopping trip when she could not find anything to suit her needs. On assignment from the British government, he uncovered that 80% of women wear the wrong size of bra. He reported that women are measuring their chest diameter and maximum breast diameter rather than their breast volume, especially when the body is in motion. According to Tyrer, "to get the most supportive and fitted bra it's infinitely better if you know the volume of the breast and the size of the back.". He says the A, B, C, D cup measurement system is flawed. "It's like measuring a motor car by the diameter of the gas cap." "The whole design is fundamentally flawed. It's an instrument of torture." Tyrer has developed a bra design with crossed straps in the back. These use the weight of one breast to lift the other using counterbalance. Standard designs constrict chest movement during breathing. One of the tools used in the development of Tyrer's design has been a projective differential shape body analyzer for 40,000 GBP.
Contrary to popular belief, breasts weigh up to ~1 kg and not ~0.2 .. 0.3 kg. Tyrer said, "By measuring the diameter of the chest and breasts current measurements are supposed to tell you something about the size and volume of each breast, but in fact it doesn't". Bra companies remain reluctant to manufacture Tyrer's prototype, which is a front closing bra with more vertical orientation and adjustable cups.
A 2012 study by White and Scurr University of Portsmouth compared method that adds 4 to the band size over-the-bust method used in many United Kingdom lingerie shops with and compared that to measurements obtained using a professional method. The study relied on the professional bra-fitting method described by McGhee and Steele (2010).
The study utilized a 5-step approach to obtain the best fitting bra size for an individual. The study measured 45 women using the traditional selection method that adds 4 to the band size over-the-bust method. Women tried bras on until they obtained the best fit based on professional bra fitting criteria. The researchers found that 76% of women overestimated their band and 84% underestimated their cup size. When women wear bras with too big a band, breast support is reduced. Too small a cup size may cause skin irritation. They noted that "ill-fitting bras and insufficient breast support can lead to the development of musculoskeletal pain and inhibit women participating in physical activity." The study recommended that women should be educated about the criteria for finding a well-fitting bra. They recommended that women measure under their bust to determine their band size rather than the traditional over the bust measurement method.
Advertising and retail influence
Manufacturers' marketing and advertising often appeals to fashion and image over fit, comfort, and function. Since about 1994, manufacturers have re-focused their advertising, moving from advertising functional brassieres that emphasize support and foundation, to selling lingerie that emphasize fashion while sacrificing basic fit and function, like linings under scratchy lace.
Women with larger breasts (cup size greater than D) can have a difficult time finding a correctly sized bra because many stores do not offer a sufficient range of bras in greater sizes. Many salespeople are not trained in how to properly fit a bra, and when the customer can't find what they want, will sell the customer the next largest or smallest size. Some salespeople measure customers over their shirt and bra, adding errors to every measurement. Elisabeth Squires, an author of a breast-health and bra guide, says "Most really good fitters will tell you this is an art, not a science."
International fitting standards
Bra-labeling systems used around the world are at times misleading and confusing. Cup and band sizes vary around the world. In countries that have adopted the European EN 13402 dress-size standard, the torso is measured in centimetres and rounded to the nearest multiple of 5 cm. Bra-fitting experts in the United Kingdom state that many women who buy off the rack without a professional assistance wear up to two sizes too small.
|Under bust (cm)||58-62||63-67||68-72||73-77||78-82||83-87||88-92||93-97||98-102||103-107||108-112||113-117||118-122||123-127||128-132||133-142||143+|
|FR, BE, ES||75||80||85||90||95||100||105||110||115||120||125||130||135||140||145||150||155|
|US, UK (in)||28||30||32||34||36||38||40||42||44||46||48||50||52||54||56||58||60|
There are several sizing systems in different countries. Most use the chest circumferences measurement system and lettered cup sizes, but there are some significant differences. Many bras available come in only 36 sizes.
The UK uses the inch-system, this means that the difference in chest circumference between the cup sizes is always one inch, or 2.54 cm. The difference between 2 band sizes is 2 inches or 5.08 cm.
Leading brands and manufacturers including Panache, Bestform, Gossard, Freya, Curvy Kate, Bravissimo and Fantasie, which use the British standard band sizes 28-30-32-34-36-38-40-42-44, and so on. Cup sizes are designated by AA-A-B-C-D-DD-E-F-FF-G-GG-H-HH-J-JJ-K-KK-L.
However, some clothing retailers and mail order companies have their own house brands and use a custom sizing system. Marks and Spencers uses AA-A-B-C-D-DD-E-F-G-GG-H-J, leaving out FF and HH. As a result, their J-Cup is equal to a British standard H-cup. Evans and ASDA sell bras (ASDA as part of their George clothing range) whose sizing runs A-B-C-D-DD-E-F-G-H. Their H-Cup is roughly equal to a British standard G-cup.
Some retailers reserve AA for young teens, and use AAA for ladies.
Australia / New Zealand
Australia and New Zealand use a permutation of the British system. Cup sizes are the same, but Australia's bra band measurement system is based on dress sizing charts. However, dress sizes and cuts are calculated for B and C cups only, so basing the choice of band size upon dress size is not an accurate way to get the bra size. Depending upon a woman's build, a size 16 may wear a 16 C (UK 40 C), a 14 DD, 12 F or a 10 G (UK 34 G) underneath her clothes, because all bra sizes are made for the same chest circumference of approx. 40 inches.
United States and Canada
Bra-sizing in the United States and Canada is very similar to the United Kingdom. Band sizes use the same designation in inches and the cups also increase by 1-inch-steps. However, some manufacturers use conflicting sizing methods. Some label bras beyond a C cup as D-DD-DDD-DDDD-E-EE-EEE-EEEE-F…, some use the variation: D1, D2, D3, D4, D5..... but many use the following system: A, B, C, D, DD, DDD, G, H, I, J, K, L, M, N, O. and others label them like the British system D-DD-E-EE… Comparing the larger cup sizes between different manufacturers can be difficult.
In 2013, underwear maker Jockey International entered the North American bra market with the first change to the standard sizing system since it was introduced in the 1930s. Its bras will be sold with ten cup sizes per band size, numbered rather than lettered, designated as 1-36, 2-36 etc. The system took the company eight years to develop, which involved scans of the breasts and torsos of 800 women, many of whom researchers also followed into their homes as they chose bras and put them on, taking note of their complaints.
To introduce the system, Jockey is selling a set of plastic cups online for women to use to find their new cup size. Some analysts were critical of that aspect, since it imposed a $20 entry fee to adoption of the system on top of the $60 cost of the bras themselves. Jockey hopes to offset that by offering a coupon with it equivalent to the cost of the cups and a money-back guarantee should the bra not fit.
|Underbust circumference||Bust size||Underbust size|
In Continental Europe the torso is measured in centimetres and rounded to the nearest multiple of 5 cm. Band sizes run 65-70-75-80…, increasing in steps of 5 cm, similar to the English double inch. A woman with a loosely measured underbust circumference of 78–82 cm should wear a band size 80.
The cup labels begin with 'AA' for an 11±1 cm difference between bust and underbust circumference, i.e. not between bust circumference and band size as in the English systems. They increase in steps of 2 cm, instead of 2.5 cm or 1-inch, and except for the initial cup size letters are neither doubled nor skipped. In very large cup sizes this causes smaller cups than their English counterparts.
This system has been standardized in the European dress size standard EN 13402 introduced in 2006, but was in use in many European countries before that date.
South Korea / Japan
In South Korea and Japan the torso is measured in centimetres and rounded to the nearest multiple of 5 cm. Band sizes run 65-70-75-80…, increasing in steps of 5 cm, similar to the English double inch. A woman with a loosely measured underbust circumference of 78–82 cm should wear a band size 80.
The cup labels begin with 'AAA' for an 5±1.25 cm difference between bust and underbust circumference, i.e. simillar bust circumference and band size as in the English systems. They increase in steps of 2.5 cm, and except for the initial cup size letters are neither doubled nor skipped.
Japanese sizes are the same as Korean ones, but the cup labels begin with 'AA' for an 7.5±1.25 cm difference and usually precedes the bust designation, i.e. 'B75' instead of '75B'.
This system has been standardized in the Korea dress size standard KS K9404 introduced in 1999 and in Japan dress size standard JIS L4006 introduced in 1998.
France / Belgium / Spain
The French and Spanish system is a permutation of the Continental European sizing system. While cup sizes are the same, band sizes are exactly 15 cm larger than the European band size.
The Italian band size uses small consecutive integers instead of the underbust circumference rounded to the nearest multiple of 5 cm. Since it starts with size 0 for European size 60, the conversion consists of a division by 5 and then a subtraction of 12. The size designations are often given in Roman numerals.
Cup sizes have traditionally used a step size of 2.5 cm, which is close to the English inch of 2.54 cm, and featured some double letters for large cups, but in recent years some Italian manufacturers have switched over to the European 2-cm system.
Calculating cup volume and breast weight
If a cup is a hemisphere, its volume V is given by the following formula:
where r is the radius of the cup, and D is its diameter.
If the cup is an hemi-ellipsoid, its volume is given by the formula :
where a, b and c are the three semi-axes of the hemi-ellipsoid, and cw cd and wl are respectively the cup width, the cup depth and the length of the wire.
Cups give a hemi-spherical shape to breasts and underwires give shape to cups. So the curvature radius of the underwire is the key parameter to determine volume and weight of the breast. The same underwires are used for the cups of sizes 36A, 34B, 32C, 30D etc. ... so those cups have the same volume. The reference numbers of underwire sizes are based on a B cup bra, for example underwire size 32 is for 32B cup (and 34A, 30C...). An underwire size 30 width has a curvature diameter of 3-inch 5/6 ≈ 9.7 cm and this diameter increases by ⅓ inch ≈ 0.847 cm by size. The table below shows volume calculations for some cups that can be found in a ready-to-wear large size shop.
|Underwire size||Bra size (US system)||Bra size (UK system)||Cup diameter||Volume of one cup||Weight of both breasts|
|30||32A 30B 28C||32A 30B 28C||9.7 cm (3 in 5/6)||240 cc (0.51 US pt)||0.43 kg (0.95 lb)|
|32||34A 32B 30C 28D||34A 32B 30C 28D||10.6 cm (4 in 1/6)||310 cc (0.66 US pt)||0.56 kg (1.2 lb)|
|34||36A 34B 32C 30D 28E||36A 34B 32C 30D 28DD||11.4 cm (4 in 1/2)||390 cc (0.82 US pt)||0.70 kg (1.5 lb)|
|36||38A 36B 34C 32D 30E 28F||38A 36B 34C 32D 30DD 28E||12.3 cm (4 in 5/6)||480 cc (1.0 US pt)||0.86 kg (1.9 lb)|
|38||40A 38B 36C 34D 32E 30F 28G||40A 38B 36C 34D 32DD 30E 28F||13.1 cm (5 in 1/6)||590 cc (1.2 US pt)||1.1 kg (2.4 lb)|
|40||42A 40B 38C 36D 34E 32F 30G 28H||42A 40B 38C 36D 34DD 32E 30F 28FF||14.0 cm (5 in 1/2)||710 cc (1.5 US pt)||1.3 kg (2.9 lb)|
|42||44A 42B 40C 38D 36E 34F 32G 30H 28I||44A 42B 40C 38D 36DD 34E 32F 30FF 28G||14.8 cm (5 in 5/6)||850 cc (1.8 US pt)||1.5 kg (3.3 lb)|
|44||44B 42C 40D 38E 36F 34G 32H 30I 28J||44B 42C 40D 38DD 36E 34F 32FF 30G 28GG||15.7 cm (6 in 1/6)||1,000 cc (2.1 US pt)||1.8 kg (4.0 lb)|
|46||44C 42D 40E 38F 36G 34H 32I 30J 28K||44C 42D 40DD 38E 36F 34FF 32G 30GG 28H||16.5 cm (6 in 1/2)||1,180 cc (2.5 US pt)||2.1 kg (4.6 lb)|
|48||44D 42E 40F 38G 36H 34I 32J 30K 28L||44D 42DD 40E 38F 36FF 34G 32GG 30H 28HH||17.4 cm (6 in 5/6)||1,370 cc (2.9 US pt)||2.5 kg (5.5 lb)|
|50||44E 42F 40G 38H 36I 34J 32K 30L 28M||44DD 42E 40F 38FF 36G 34GG 32H 30HH 28J||18.2 cm (7 in 1/6)||1,580 cc (3.3 US pt)||2.8 kg (6.2 lb)|
|52||44F 42G 40H 38I 36J 34K 32L 30M 28N||44E 42F 40FF 38G 36GG 34H 32HH 30J 28JJ||19.0 cm (7 in 1/2)||1,810 cc (3.8 US pt)||3.3 kg (7.3 lb)|
|54||44G 42H 40I 38J 36K 34L 32M 30N 28O||44F 42FF 40G 38GG 36H 34HH 32J 30JJ 28K||19.9 cm (7 in 5/6)||2,060 cc (4.4 US pt)||3.7 kg (8.2 lb)|
|56||44H 42I 40J 38K 36L 34M 32N 30O 28P||44FF 42G 40GG 38H 36HH 34J 32JJ 30K 28KK||20.7 cm (8 in 1/6)||2,340 cc (4.9 US pt)||4.2 kg (9.3 lb)|
|58||44I 42J 40K 38L 36M 34N 32O 30P||44G 42GG 40H 38HH 36J 34JJ 32K 30KK||21.6 cm (8 in 1/2)||2,640 cc (5.6 US pt)||4.8 kg (11 lb)|
|60||44J 42K 40L 38M 36N 34O 32P||44GG 42H 40HH 38J 36JJ 34K 32KK||22.4 cm (8 in 5/6)||3,000 cc (6.3 US pt)||5.3 kg (12 lb)|
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