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.

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, directly under your bust. Keep the tape level and parallel to the floor.

When you put on a bra, lean forward and use your hands to pull all your breast tissue from the sides into the cups. This ensures you’re actually sitting in the bra correctly before you judge the fit.

Your breasts should fill the cups without "quad-boobing" (spilling over the top) or gaping (extra space at the top).

The center piece between the cups should sit flat against your breastbone. If it’s hovering, the cups are likely too small.