Gaping is excess length along the neckline edge, and the fix is to remove that length on the pattern before cutting rather than to take it out at the shoulder seam.
Why the shoulder seam is the wrong place. Deepening the shoulder seam shortens the whole front and pulls the armhole out of shape. The excess is at the edge only, so that is where it has to go.
The pattern fix. Draw two or three lines from the neckline edge towards the bust point or towards the armhole. Slash along them, leaving a hinge at the far end, and overlap the neckline edge by a few millimetres at each cut until the edge lies flat. The overlapped amount is transferred into the dart or into the armhole ease, where it disappears into the shaping. Redraw the neckline as a smooth curve.
How much to remove. Pin the gape out on a toile with the garment on, measure the pinned amount, and distribute it across the cuts. Typically 5 to 15 mm in total.
If the garment is already cut, three things help. Stay-stitch the neckline just inside the seam line as soon as it is cut, which stops the bias edge stretching further. Cut the facing or binding very slightly shorter than the neckline and ease the garment onto it. And clip a fitted facing so it lies flat rather than pulling.
Interfacing the neckline edge on a woven garment prevents most gaping in the first place.
Questions people actually ask
Is gaping always a fitting fault?
No. A bias neckline that has stretched during handling gapes even in the right size. Stay-stitch immediately after cutting to prevent it.
Where does the removed length go?
Into an existing dart, into armhole ease, or into a new small dart. It is rotated away rather than deleted, so the bust shaping is preserved.
Last reviewed 2026-08-11