It should be level all the way around. If it arches up your back, the band is too big. You should be able to fit two fingers underneath it.
Wrap a measuring tape snugly around your ribcage, directly under your bust. Keep the tape level and parallel to the floor. how to buy correct bra size
The center piece between the cups should sit flat against your breastbone. If it’s hovering, the cups are likely too small. It should be level all the way around
Subtract your calculated band size from this bust measurement . Each inch of difference represents a cup size: 1 inch = A 2 inches = B 3 inches = C 4 inches = D (and so on) 3. The "Fit Check" (The Most Important Part) Wrap a measuring tape snugly around your ribcage,
If the number is even, add 0. If it’s odd, add 1. (Example: 31" becomes a 32 band). 2. Measure Your Cup Size
Wrap the tape loosely around the fullest part of your chest. Don’t pull it tight—just ensure it’s level all the way around.
Numbers are just a starting point; the mirror tells the truth. Look for these signs of a good fit: