How to Blend Sewing Pattern Sizes when there are Darts or Pleats


HI Ho my lovely sew’ist friends – My post today is about how to blend your sewing pattern sizes when there are darts or pleats in play.

And as I have just released a stunning new pattern – the Camelia Draped Jersey Dress – I am going to use the Camelia as an example.

The dress has both pleated folds and darts in the side seam –  the pleated folds are part of the design element of the dress and the side bust dart gives the dress a much needed contour to create its gorgeous shape.

If you have missed my 3 previous posts in celebration of the Camelia Dress release be sure to check out the following posts.
1. Darts Are Essential Shaping Tools
2. Camelia Dress Pattern Tester Roundup Part 1
3. Camelia Dress Pattern Tester Roundup Part 2


The Anatomy of a Side Bust Dart

The above picture shows a dart sitting in the side seam. In my previous post you would have read that I love darts as they give such fabulous shaping – and I especially love bust darts. A dart consists of it apex point – closest to the nipple – 2 dart legs that create the width of the dart and the dart end – or I like to call it the dart cap/hat. The end of the dart always has a pointed formation which reflects/mirrors the edge that it will fold down onto to align itself to the side seam.

The above image on the left shows what a dart cap/hat SHOULD NOT look like. It is a random point that is cut out in a haphazard way.

The image on the right shows what a dart cap/hat should look like after it has been “proved” (trued = term in the US)

The upper half of the dart value is a continuation of the upper side seam. The lower half of the dart value is a mirror of the lower side seam where it folds down onto it.


Blending Pattern Sizes at the Side Seam with Darts or Pleats.


The above image shows the nested pattern of the right front of the new Camelia Dress. The right side of the pattern has 6 folded pleats as part of the design. And it can get quite tricky to ascertain what lines should be used for a particular size.

The image above shows 2 pattern sizes in play – a size 5 and a size 8 from our sizing chart. Even though it is clearer and you can see where the pleat lines are indicated it will still be tricky to blend from a size 5 down to a size 8 at the hips while still keeping the integrity of pleated folds in it exact formation.

So read on for my easy way of blending sizes. It is the most accurate and sound way of handling design details like this.

Step 1. Mark the pleat line for you desired size. Here I have marked pleat lines for the size of my hips.

Step 2. Fold the pleats as indicated in the sewing instructions. Hold with adhesive tape. Fold under the right front edge and hold with adhesive tape. Also fold the right side bust dart and hold with adhesive tape.

Step 3. Fold under the left front edge and hold with adhesive tape. Also fold the left side bust dart and hold with adhesive tape.

Step 4. Lay the right front pattern over the left front pattern matching waistline notch of right side to left side waist notch. Make sure side seams are matching – use sewing pins to hold in place pin.

Step 5. Draw your size transition onto the right side front. As an example here I am transitioning from a Designer Stitch size 5 down to a size 8. The above image shows I have colour blocked out my size transition.

Step 6. Trim off the right side seam size transition where is it has been colour blocked.

Step 7. Now you can remove adhesive tape. You will see that the integrity of your proved folds – pleats – have been maintained and also the right side bust dart has also been maintained in its “proved” formation on the under wrapped left front pattern piece.

You would then match up the left side seams to blend your sizes so you can maintain the “proved” left side seam bust dart in the same manner as above.

Now wasn’t that EASY my friends !!!….You are being totally accurate while maintaining the integrity of both the bust darts and the right side seam folded pleats.

This method can be used wherever you have darts/pleats/folds anywhere on the perimeter of a pattern piece when you have to blend between sizes.


And the details of Camelia Dress :

The Camelia Dress is for a sewing level of Confident Advanced Beginner and Above.

On Sale for a limited time only – $8.75 (US)
(AU/UK) 6 – 28
(US) 2 – 24
(EU) 34 – 56
Cup Sizes – B, C, D, DD

Lots of love to you.
Cheerio xx
Ann at Designer Stitch,


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