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. 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. Wrap a measuring tape snugly around your ribcage,
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. This ensures you’re actually sitting in the bra
Your breasts should fill the cups without "quad-boobing" (spilling over the top) or gaping (extra space at the top).