To begin, measure the volume under the breast, or in other words, the circumference of the back. In this case, tape measure should be held parallel to the floor, adhering tightly to the body directly under the bust. In no case do not slouch when measuring. Make a note of that number. It shall conform to the figures appearing on the label bra. When this step is 5 cm, so it is possible when choosing a bra you have round measuring the volume under the breast. For example, if you have a grasp of the back is 82 cm, you need to buy a bra, which shows the number 80.
In addition to wrap back to the proper selection of lingerie and need to know the fullness of the cup. It is defined as the difference between the volume of the chest and under the breast volume, so the second should be measured - this chest at its most protruding points. Get the number, subtract from it your volume under the breast. If the difference is 10-12 cm - your size AA (or 0), 12-13 cm - A (1), 13-15 cm - B (2), 15-17 cm - C (3), 18-20 cm - D (4), 20-22 cm - E (5).
Knowing these two measurements, you can pick up a bra size you want. But do not forget that different firms and manufacturers labeling may vary. In addition, the same style of bra can approach a woman, but not to approach the other, even if they have breast size is the same, so if possible, always try on lingerie before you buy.