For those of you with a scientific bent of mind, this snippet from Wikipedia will explain why these cups have the same size: 38A = 36B = 34C = 32D = 30DD = 28E
and why each of these cups is bigger that the precedent: 28C < 30C < 32C < 34C < 38C
Cups give a hemi sperical 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 underwire are used for the cup of size 36A, 34B, 32C, 30D and etc... so those cup have the same volume. The reference number of underwire size are based on B cup bra, for example underwire size 32 is for 32B cup (and 34A, 30C...). An underwire size 30 with has a curvature diameter of 3 inch 5/6 ≈ 9.7 cm and this diameter increase of ⅓ inch ≈ 0.847 cm by size. The table below is fill with all the size that can be find in ready to wear large size shop
| Underwire size | Bra size | Cup diameter | Volume of one cup | Weight of both breasts |
|---|---|---|---|---|
| 30 | 32A 30B | 9.7 cm (3 in 5/6) | 240 cc (0.51 US pt) | 0.43 kg (0.95 lb) |
| 32 | 34A 32B 30C | 10.6 cm (4 in 1/6) | 310 cc (0.66 US pt) | 0.56 kg (1.2 lb) |
| 34 | 36A 34B 32C 30D | 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 | 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 | 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 | 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 | 14.8 cm (5 in 5/6) | 850 cc (1.8 US pt) | 1.5 kg (3.3 lb) |
| 44 | 46A 44B 42C 40D 38E 36F 34G 32H 30I | 15.7 cm (6 in 1/6) | 1,000 cc (2.1 US pt) | 1.8 kg (4.0 lb) |
| 46 | 48A 46B 44C 42D 40E 38F 36G 34H 32I 30J | 16.5 cm (6 in 1/2) | 1,180 cc (2.5 US pt) | 2.1 kg (4.6 lb) |
| 48 | 50A 48B 46C 44D 42E 40F 38G 36H 34I 32J 30K | 17.4 cm (6 in 5/6) | 1,370 cc (2.9 US pt) | 2.5 kg (5.5 lb) |
| 50 | 52A 50B 48C 46D 44E 42F 40G 38H 36I 34J 32K | 18.2 cm (7 in 1/6) | 1,580 cc (3.3 US pt) | 2.8 kg (6.2 lb) |
| 52 | 52B 50C 48D 46E 44F 42G 40H 38I 36J 34K 32L | 19.0 cm (7 in 1/2) | 1,810 cc (3.8 US pt) | 3.3 kg (7.3 lb) |
| 54 | 54B 52C 50D 48E 46F 44G 42H 40I 38J 36K 34L 32M | 19.9 cm (7 in 5/6) | 2,060 cc (4.4 US pt) | 3.7 kg (8.2 lb) |
| 56 | 56B 54C 52D 50E 48F 46G 44H 42I 40J 38K 36L 34M 32N | 20.7 cm (8 in 1/6) | 2,340 cc (4.9 US pt) | 4.2 kg (9.3 lb) |
| 58 | 58B 56C 54D 52E 50F 48G 46H 44I 42J 40K 38L 36M 34N | 21.6 cm (8 in 1/2) | 2,640 cc (5.6 US pt) | 4.8 kg (11 lb) |
| 60 | 58C 56D 54E 52F 50G 48H 46I 44J 42K 40L 38M 36N | 22.4 cm (8 in 5/6) | 3,000 cc (6.3 US pt) | 5.3 kg (12 lb) |
