Breasts are shaped differently, and cups hold volume. Measuring without a bra won't always capture the volume either, especially for breasts that sag a bit or f

Breasts are shaped differently, and cups hold volume. Measuring without a bra won't always capture the volume either, especially for breasts that sag a bit or flatten out some when not wearing a bra (very common for larger breasts). Breasts tend to simply "sit" differently in a bra than without - more mass in front of the arm, for example. Even a poorly fitted bra will give a better starting point than measuring braless. And really, that's what this is: A starting point. Go with the best starting point that is available to you. You already are going to try on all of the ones that might work, you might as well narrow that down.