Sewing Tips

Trueing the Shoulder

Quick post here: I just downloaded a new pattern release with a square neckline, which I love…..however the neckline wasn’t trued at the shoulder front-to-back. “Trueing” is the finishing step in patternmaking that ensures seam corners measure 90-degrees (a “true” right angle) so that when a seam is stitched, the result is a smooth edge line without peaks or jagged edges. There is an easy fix, so let me show you how to true the neckline in case you ever run into this issue with a similar style.

Here is the front bodice: notice that the shoulder at the neckline ends in an acute angle (marked in red….about 85 degrees):

Front and back bodices have the same armscye and shoulder, which means that after stitching the shoulder seam, the result will not be a smooth 180-degree line (a straight line) but instead will be about 170-degrees:

What will that look like? Connected front-to-back, the shoulder will have a peak pointing towards the neck, instead of a smooth line:

To check the fit on a dressform it helps to remove the seam allowances:

Here’s what happens on the form: the armscye-at-shoulder has a smooth line, but the neckline-at-shoulder does not, it pokes out towards the neck:

You can quickly smooth the neckline and get rid of the angled peak by “trueing” the corners, using a basic French curve:

Trim off the peak bits:

Check the fit by putting the pattern back on the dressform: see how much smoother the neckline fits over the shoulder?


In real life you don’t need to remove the seam allowance to make this quick fix. You can mark the seam allowances:

Fold back the seam allowances and connect the front to back bodices at the shoulder:

True the corners with your French curve:

Trim off the jagged points:

And voila! Your pattern is trued at the shoulder:

If you don’t have a French curve you can still do this adjustment with a straight edge. Mark and fold your seam allowances at the shoulder:

Connect the shoulder front to back as if you were stitching the shoulder seam. Then use a ruler or straight-edge to establish the width of the straps:

Slide your straight-edge down and mark the same distance from the armscye as you go:

Continue down from the back armscye to the front armscye:

Trim off the jagged bits:

And done, nice and smooth neckline going over the shoulder:


I’ve written several posts about trueing before. If this is something you are interested in, just type the word “trueing” in the search bar.

Happy Sewing!


Leave a Reply

Your email address will not be published. Required fields are marked *