Fitting a swayback: How to get rid of the folds on the back of your dress

Try standing with your side to a mirror. Or have a friend take a picture of you from the side. Is your back straight? Completely straight? Or do you have curves, making you almost the shape of an S?

Most women do. So you might think it’s a bit strange that so many close fitting dresses have a straight centre-back.. .(Exceptions are for instance MariaDenmark 407 Annika Dress and the knit dress in Sysiden #23)

Because what happens if your back is curved, but wear a close fitting dress that is straight is this (only usually a bit more, because this dress actually is shaped a bit):

A curved back with a straight centre-back

The fabric is going to fall in folds across the back – in a not very flattering way.

Well, it’s thankfully super easy to fix in the pattern!


How to do the swayback alteration and remove the folds on the back

Put on your dress (the muslin). Make a fold at centre-back so the dress becomes smooth and the side seams are straight. Pin the fold at centre-back to keep the fold in place.

How much of a sway-back alteration do you need?


Take of the muslin and get out your back piece. If you are using a pattern with seam allowances included, you need to measure out and draw in the seam-lines before moving on!

Ready for a swayback alteration

In this tutorial, I’m showing the technique on a jersey dress with a straight centre-back. But it’s the same for any type of dress.


First you need to figure out where on the pattern, you are going to make your alteration. Meaning where on the back, you have excess fabric.

Begin by marking the placement of the pin on both sides of your fabric. Use a marker or extra pins. Fold out the fabric and measure the distance between the two markings and their placement on the centre-back line (measure from the waistline, if you have that marked, or measure from the neckline and down). Measure on the fabric and transfer the measurements to the pattern piece.


Markings for swayback on the pattern

Draw the markings on the pattern at centre-back

Transfer the placement of the pin and the amount of fabric you pinned, to your back pattern piece


Locate the midway point of the two markings and draw a straight line from that and across the back piece to (but not through) the side seam.

Draw two lines, one from each marking to the point in the side seam where the first line ended.

Swayback alteration - draw lines to the side seam

Draw lines to the side seam


Making the swayback alteration

Cut along the top most line to, but not through, the side seam.

Cut for swayback alteration

Cut along one of the lines to the side seam, but NOT through


Also cut from the seam allowance to, but not through, the side seam. This will give you a small hinge of paper that makes it possible to move the pieces.

cut for swayback alteration

Cut the seam allowance to, but not through, the seam line.


Now turn the top piece down to the bottom most line, so that the pieces overlap. This will remove the excess fabric.

overlap the pieces for swayback alteration

Place the two lines on top of each other, to overlap the paper. Tape it in place.

Now you just need to correct the grainline and maybe even out the seam line so it that it is curved. The grainline needs to be perpendicular to the hem of the dress.

grain line after swayback

Re-draw the grainline and even out the seam lines if they are jagged.


And that’s it!

The next dress you sew from the pattern will be without folds on the back.


After swayback alteration - MariaDenmark 407

P.S. You don’t need to sew a new muslin because of the swayback each time you make a new pattern. If you, for example, now know that you need to remove 3 cm  when there is a straight centre back seam in a jersey dress, you can count on that being the case for any jersey dress with a straight centre back seam.

P.P.S Want more fitting help? Then take a look at Foundation of Fitting, my e-book on fitting.