Ways of measuring breast sizes vary, but they follow certain conventions. The bra size is denoted by a letter and numbers. The letter refers to the breast cup and the number the band size. However, the measurements are not the same; in the US, the size is measured in inches. In most European countries, it is in centimeters.
Band Size Measurements
The following illustrates the difference in how bra sizes are measured. The XS size in the US and the UK is 28 in. In other EU countries, that would be 60 cm. 30 inches in the US and UK is small (S); this is equal to 65 cm (S). In France it is 80 cm.
The band / breast size indicators for the US and UK and their letter designation are the following: 32 (M), 34 (L), 36 (XL), 38 (XXL), 40 (3XL), 42 (4XL), 44 (5XL) and 46 (6XL).
In the EU standard EN 13402, the sizes are as follows (in cm): 70 (M), 75 (L), 80 (XL), 85 (XXL), 90 (3XL), 95 (4XL) 100 (5XL) and 105 (6XL). In France, the band size indicators are 85 (M), 90 (L), 95 (XL), 100 (XXL), 105 (3XL), 110 (4XL), 115 (5XL) and 120 (6XL).
The following illustrate the letters used in cup sizes and the difference in inches between the bust and band size. For AA cup size (US and Canada), the difference between bust / breast size and the band size is less than an inch (10–12 cm in European cup measurements).
For A cup, the difference is 1 inch (12–14 cm). For cup B, it is 2 inches (14–16 cm). For cup C, it is 3 inches (16–18 cm). For cup D it is 4 inches (18–20 cm). For DD or E (DD in Australia and the UK) it is 5 inches (20–22 cm).
For cup size DDD or F (E in Australia and the UK), it is 6 inches (22–24 cm). For cup G (F in the UK and Australia), it is 7 inches (24–26 cm). For breast size cup H (FF in the UK), the difference is 8 inches (26–28 cm.
For cup I (G in the UK) the difference is 9 niches (28–30 cm). For cup J (GG in the UK and Australia) the difference is 10 inches (30–32 cm). For cup size K (H in the UK and Australia) the difference is 11 inches (32–34 cm).
For cup L (HH in the UK and Australia), the difference is 12 inches (34–36 cm). For cup M (J in the UK), the difference is 13 inches (36–38 cm). For cup size N (JJ in the UK), the difference is 14 inches (38–40 cm).
The breast sizes shown here is only a general guide. Even if two bra companies advertise their product as 36C, it may feel different. It’s important to verify the fitting and not just consider the labeling.