Just figured Id post this for all of us this is how you measure yourself, or have hubby help, (Vickies Manager in the past). With measuring tape or a ribbon, with or without a bra I usually do without, measure rib cage for the band size; straight around the ribs right below the breast, make sure its as straight as possible. If number is even then most likely your band size if odd number round up same goes for in betweens. Then around the FULLEST part of your breast, normally about the nipple line; for the bust size. Then take the 2 numbers and figure out the difference by subtracting band from bust. The difference between the two is the cup size, use these calculations.

0 to 1.5 inches = A, 1.5 to 2.5 = B, 2.5 to 3.5 = C, 3.5 to 4.5 = D, 4.5 to 5.5 = DD/E, 5.5 to 6.5 = F, 6.5 to 7.5 = G, 7.5 to 8.5= H,8.5 to 9.5 = I, 9.5 to 10.5 = J,
10.5 to 11.5 = K

So for me my band was 34 and bust was almost 39, so thats a difference of around 5 makes me a full D. If you have trouble finding a bra that fits you can mess with the sizing aka if you measure a 34D and are finding them uncomfortable if you go UP a band size to 36 then go down a cup size that might work. You dont really want to mess with band sizing too much through because then youll find things like the straps being uncomfortably under your arm pits and digging in. Also as we get bigger go for the bra with the thicker straps.