Glad you asked...
In order to measure correctly to find your bra size, you will need a flexible seamstresses measuring tape. There are two measurements you will need to take and the combination of both will give you an idea of what size you need. Keep in mind though, that every body is different, and usually breast vary slightly so you will need to choose your bra by how it fits you when you try it on. Measure around your chest directly under your breasts, exhale before you take this final measurement because you want it to be the smallest possible measurement, as bra materials tend to stretch over time, you'll want your new ones to fit snugly. If the measurement comes up to an odd number add 5, if it is an even number add 4. Scribble this number down and then measure for your cup size. Measure around the fullest part of your breast, rounding fractions up. Subtract your first measurement from your second, and the difference will give you your cup size. You can find more info at:
http://www.herroom.com/marketing/measure...