How to measure correctly
Remember that you will get only an approximate size of bra with this measurement. Each bra is a little different style, shape, etc. There are bras of different brands on the market and therefore the bra size could be slightly different with each brand.
This guide will help you to find at least size of the bra, which you should try first.
Step 1: Measure for band size
First measure the chest under the breasts with measuring tape. Make sure that the measuring tape is parallel with the ground. Band size has to be measured tightly and on the exhale.
Remember that the measured value is not your final value of the bra band. The bra band should be about 5-10cm shorter than the measured size. You need to have in mind the elasticity of the material as well as it loses its elasticity with washing and wearing.
So, for example, if you measured your band size 78cm, your bra band size shoudl be 70. A new bra should be always worn with the last hook (that means the loosest bra band) and it should fit firmly. Over time your bra will lose its elasticity and then you can use the other hooks to make it firm again.
Step 2: Measure for cup size
Measure your cup size at the fullest part of your bust wearing no bra. If you have big or sagging breasts you can measure the cup size while wearing non-padded bra. Make sure that the measuring tape is parallel with the ground.
The final size can be found here
Not sure what size do you have? Let's ask in the Advice room!
To find out whether your bra fits properly, you need to have it properly dressed! For more, see How to wear a bra correctly!
An advice:
For example, you measured 80cm under your breasts and 94cm as your cup size. According to The right bra size table your bra size comes out as 70E (32E). As pointed out before, the band size must be 5-10cm smaller than the size measured. However, if you try more bras with band size 70 (I suppose you are wearing a bra correctly and on the last hook) and your bra is so tight that it cause more discomfort, let's try a larger band - size 75 (34). But you can't try size 75E (34E)! Cup size should be proportionately smaller if we increase the band size (for example 80B '36B' and 70D '32D' have quite the same size of cups). That means you can try a cup size smaller - size 75D (34D).