<P> 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 1⁄3 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 . </P> <Table> <Tr> <Th> Underwire size </Th> <Th> Bra size (US system) </Th> <Th> Bra size (UK system) </Th> <Th> Cup diameter </Th> <Th> Volume of one cup </Th> <Th> Weight of both breasts </Th> </Tr> <Tr> <Td> 30 </Td> <Td> 32A 30B 28C </Td> <Td> 32A 30B 28C </Td> <Td> 9.7 cm (3 in 5 / 6) </Td> <Td> 240 cm (0.51 US pt) </Td> <Td> 0.43 kg (0.95 lb) </Td> </Tr> <Tr> <Td> 32 </Td> <Td> 34A 32B 30C 28D </Td> <Td> 34A 32B 30C 28D </Td> <Td> 10.6 cm (4 in 1 / 6) </Td> <Td> 310 cm (0.66 US pt) </Td> <Td> 0.56 kg (1.2 lb) </Td> </Tr> <Tr> <Td> 34 </Td> <Td> 36A 34B 32C 30D 28E </Td> <Td> 36A 34B 32C 30D 28DD </Td> <Td> 11.4 cm (4 in 1 / 2) </Td> <Td> 390 cm (0.82 US pt) </Td> <Td> 0.70 kg (1.5 lb) </Td> </Tr> <Tr> <Td> 36 </Td> <Td> 38A 36B 34C 32D 30E 28F </Td> <Td> 38A 36B 34C 32D 30DD 28E </Td> <Td> 12.3 cm (4 in 5 / 6) </Td> <Td> 480 cm (1.0 US pt) </Td> <Td> 0.86 kg (1.9 lb) </Td> </Tr> <Tr> <Td> 38 </Td> <Td> 40A 38B 36C 34D 32E 30F 28G </Td> <Td> 40A 38B 36C 34D 32DD 30E 28F </Td> <Td> 13.1 cm (5 in 1 / 6) </Td> <Td> 590 cm (1.2 US pt) </Td> <Td> 1.1 kg (2.4 lb) </Td> </Tr> <Tr> <Td> 40 </Td> <Td> 42A 40B 38C 36D 34E 32F 30G 28H </Td> <Td> 42A 40B 38C 36D 34DD 32E 30F 28FF </Td> <Td> 14.0 cm (5 in 1 / 2) </Td> <Td> 710 cm (1.5 US pt) </Td> <Td> 1.3 kg (2.9 lb) </Td> </Tr> <Tr> <Td> 42 </Td> <Td> 44A 42B 40C 38D 36E 34F 32G 30H 28I </Td> <Td> 44A 42B 40C 38D 36DD 34E 32F 30FF 28G </Td> <Td> 14.8 cm (5 in 5 / 6) </Td> <Td> 850 cm (1.8 US pt) </Td> <Td> 1.5 kg (3.3 lb) </Td> </Tr> <Tr> <Td> 44 </Td> <Td> 44B 42C 40D 38E 36F 34G 32H 30I 28J </Td> <Td> 44B 42C 40D 38DD 36E 34F 32FF 30G 28GG </Td> <Td> 15.7 cm (6 in 1 / 6) </Td> <Td> 1,000 cm (2.1 US pt) </Td> <Td> 1.8 kg (4.0 lb) </Td> </Tr> <Tr> <Td> 46 </Td> <Td> 44C 42D 40E 38F 36G 34H 32I 30J 28K </Td> <Td> 44C 42D 40DD 38E 36F 34FF 32G 30GG 28H </Td> <Td> 16.5 cm (6 in 1 / 2) </Td> <Td> 1,180 cm (2.5 US pt) </Td> <Td> 2.1 kg (4.6 lb) </Td> </Tr> <Tr> <Td> 48 </Td> <Td> 44D 42E 40F 38G 36H 34I 32J 30K 28L </Td> <Td> 44D 42DD 40E 38F 36FF 34G 32GG 30H 28HH </Td> <Td> 17.4 cm (6 in 5 / 6) </Td> <Td> 1,370 cm (2.9 US pt) </Td> <Td> 2.5 kg (5.5 lb) </Td> </Tr> <Tr> <Td> 50 </Td> <Td> 44E 42F 40G 38H 36I 34J 32K 30L 28M </Td> <Td> 44DD 42E 40F 38FF 36G 34GG 32H 30HH 28J </Td> <Td> 18.2 cm (7 in 1 / 6) </Td> <Td> 1,580 cm (3.3 US pt) </Td> <Td> 2.8 kg (6.2 lb) </Td> </Tr> <Tr> <Td> 52 </Td> <Td> 44F 42G 40H 38I 36J 34K 32L 30M 28N </Td> <Td> 44E 42F 40FF 38G 36GG 34H 32HH 30J 28JJ </Td> <Td> 19.0 cm (7 in 1 / 2) </Td> <Td> 1,810 cm (3.8 US pt) </Td> <Td> 3.3 kg (7.3 lb) </Td> </Tr> <Tr> <Td> 54 </Td> <Td> 44G 42H 40I 38J 36K 34L 32M 30N 28O </Td> <Td> 44F 42FF 40G 38GG 36H 34HH 32J 30JJ 28K </Td> <Td> 19.9 cm (7 in 5 / 6) </Td> <Td> 2,060 cm (4.4 US pt) </Td> <Td> 3.7 kg (8.2 lb) </Td> </Tr> <Tr> <Td> 56 </Td> <Td> 44H 42I 40J 38K 36L 34M 32N 30O 28P </Td> <Td> 44FF 42G 40GG 38H 36HH 34J 32JJ 30K 28KK </Td> <Td> 20.7 cm (8 in 1 / 6) </Td> <Td> 2,340 cm (4.9 US pt) </Td> <Td> 4.2 kg (9.3 lb) </Td> </Tr> <Tr> <Td> 58 </Td> <Td> 44I 42J 40K 38L 36M 34N 32O 30P </Td> <Td> 44G 42GG 40H 38HH 36J 34JJ 32K 30KK </Td> <Td> 21.6 cm (8 in 1 / 2) </Td> <Td> 2,640 cm (5.6 US pt) </Td> <Td> 4.8 kg (11 lb) </Td> </Tr> <Tr> <Td> 60 </Td> <Td> 44J 42K 40L 38M 36N 34O 32P </Td> <Td> 44GG 42H 40HH 38J 36JJ 34K 32KK </Td> <Td> 22.4 cm (8 in 5 / 6) </Td> <Td> 3,000 cm (6.3 US pt) </Td> <Td> 5.3 kg (12 lb) </Td> </Tr> </Table> <Tr> <Th> Underwire size </Th> <Th> Bra size (US system) </Th> <Th> Bra size (UK system) </Th> <Th> Cup diameter </Th> <Th> Volume of one cup </Th> <Th> Weight of both breasts </Th> </Tr> <Tr> <Td> 30 </Td> <Td> 32A 30B 28C </Td> <Td> 32A 30B 28C </Td> <Td> 9.7 cm (3 in 5 / 6) </Td> <Td> 240 cm (0.51 US pt) </Td> <Td> 0.43 kg (0.95 lb) </Td> </Tr>

What is difference between c cup and d cup