14 August 2026
Why the cup gaps at the top
Your volume sits low in the cup and the cup spreads its volume evenly. A moulded cup holds a fixed shape, so when you are full-on-bottom the upper third has nothing to fill it. A loose band makes it worse by letting the whole cup tip away from your chest.
What is happening
Breast tissue is not distributed evenly, and moulded cups are. A moulded cup is set with the same depth top and bottom, because it is pressed over a form.
If most of your volume sits below the apex, you fill the bottom of the cup and leave air at the top. The fabric keeps the shape it was pressed into, so the gap stays visible under a t-shirt.
A loose band adds a second gap. When the band cannot hold the wires against the ribcage, the top edge of the cup falls forward and away.
How to check it on yourself
Lean forward from the hips, let everything drop into the cup, then stand up and look at the top edge without adjusting anything.
If the gap has closed, the cup volume is right and the shape is wrong. If it is still gaping after you have scooped, the cup is too big.
What to change
Move to a seamed or stretch-lace cup. A three-part cup places its seams so more depth sits below the apex, which is where your volume already is.
A half-cup or balconette cuts the upper edge lower, so there is less cup above the apex to leave empty.
Fix the band first. Snug band, then judge the cup — otherwise you are reading two problems as one.
What will not fix it
Going down a cup size. That takes volume from the bottom, where you need it, and gives you spillage at the wire.
Padding the gap or shortening the straps. Straps pull the cup up, not in, and the top edge still stands away from your chest.