You buy the shirt in your size. It fits your shoulders, your waist, your arms. Then you do up the buttons and the placket pulls open across your chest.
Here's what our fitters tell women in the fitting room every week: the shirt is almost never the problem, and neither is your body. The bra underneath it is. These are the five fit mistakes we see most, and the one fix that sorts out all of them.
The band is too big, so the weight drops forward
Most of a bra's support should come from the band, not the straps. When the band is too loose it rides up your back, and your bust drops forward and lower. That extra forward projection is exactly where your buttons pull.
Quick check: if your band rides up or you can fit more than two fingers under it, it's too big.
Your minimizer flattens you, so the shirt pulls wider
Most minimizers work by pressing you flat. But flattened tissue has to go somewhere, and it goes to the sides. You look less busty from the side but wider from every other angle, and your shirt strains across the whole chest instead of one point.
“A good minimizer doesn't squash. It gathers and centers, so you look rounder and smaller, not wider.”
Low-cut cups let tissue spill over the top
If you see a little ridge where the cup ends, that's a "boob bubble". Under a fitted shirt it reads as extra bust and pushes the fabric out. Full-coverage cups that come up higher hold everything in one smooth line.
A 3-hook band rolls under a heavy bust
Heavier busts need more anchoring. A narrow 2 or 3-hook band can roll and ride up by mid-afternoon, which drops everything forward again (see reason 1). Look for a deeper band with four hooks and a side wing that keeps it level.
It's your shape, not just your size
Two women can both wear a 36DD and need different bras. Full on top or full on the bottom, close-set or wide-set, petite frame or long torso: shape decides how a cup sits. That's why so many women find they've worn the wrong size for years once they finally get fitted. And it's why one bra keeps coming up in my fitting room.