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Jenna Dress Sewalong - Full butt adjustment / full seat adjustment

This week we're all about nailing the fit of our Jenna dresses! Just as shop bought clothes have been drafted and produced to a "standard" chart of proportions, so too are sewing patterns. Very few people will fit a pattern perfectly right out of the box, so we find it helpful to think of sewing patterns as a foundation for limitless possibilities - not only in terms of the design, but crucially in terms of the fit.

*To be taken to all the posts in the Jenna Dress sewalong, please click here*

In the last post, we showed you how to grade out or in for fuller or narrower hips. If it is just your hips that are wider, that alteration would have been enough to significantly improve the fit of the skirt of your Jenna dress. However, if the extra space is actually needed at your butt, instead of (or as well as) your hips, then today's full butt adjustment will be a better option for you. Or a combination of the two techniques if you're needing to create more space for a fuller butt and wider hips.

How do I know if I need a full butt adjustment?

There are a number of tell-tale signs to let you know that a full butt adjustment is in order - firstly, and most obviously, if you already know that you have a full, muscular, or particularly juicy booty! Other indications might include:

  • your hip measurement (around the fullest part of your butt, not around your hip bone! See this post for more on how to measure yourself accurately) falls into a larger size category than your waistline measurement
  • Hemlines often fall higher at the back instead of being level to the ground
  • you find that shop bought pencil/fitted skirts that fit on your butt are too big at the waist
  • Pencil/fitted skirts that do fit your waist tend to be very much on the snug side around your butt, and as a result they ride up and pool at the small of your back.

Ok! Let's dive right in! 

Step 1

Please note that we are using itty bitty replicas of our pattern to demonstrate - it's not full scale!

To adjust your skirt pattern to get the best fit, we need to add some extra space to all the areas that are affected by a full butt: namely, the width around the hip measurement and the length in the centre back. Some people get confused as to why extra length is needed at the centre back seam (and similarly why extra length is needed at the centre front of a bodice when doing a full bust adjustment). If you imagine that your bottom is like a hill... the fuller the booty the bigger the hill to climb, and therefore the longer the road in comparison to a flatter hill/butt. The centre back seam is the "road" that needs to be made a bit longer if it is to comfortably accommodate a fuller butt. If the centre back seam is not lengthened, the back hem will sit higher than the front.

In the same vein as a full bust adjustment, we can determine by how much we need to increase the horizontal hip measurement by starting with your waistline measurement and the size category that falls into.

For example, your waistline measurement is 26" making you a size UK 8. However, your 38" hip measurement is 2" larger than the 36" hip dictated by the size UK 8. You'll need to increase your total hip measurement by 2", making that a 1" increase to the skirt back pattern piece (which then doubles as you cut two skirt back pieces).

Start by taking your skirt back piece and marking out the allowance at the corner of the waist and side seam (shown in blue), as well as a point about 8-10" down from the waistline (shown in pink). It is across this width that the butt is usually at its fullest, and where we'll need to be creating some more space. You'll also need to mark out a point along the waistline that corresponds to the back waist dart of the bodice (also in pink). We will be creating a little dart on the back of the skirt, so it's nice if it lines up with the dart on the bodice back :)

Step 2

Draw a horizontal line through your marked point all the way from the centre back and diagonally up to where the waist and side seam meet. Stop when you hit the seam allowance line, draw a little circle to indicate a pivot point (or hinge) and continue the pink line from the circle out to the edge.

Now draw a vertical line going down from the point you marked at the waist to the horizontal line, creating another pivot point there where the two lines meet.

Step 3

Cut horizontally from the centre back and out to the side seam pivot point, and snip from the edge of the side seam to the pivot.

Cut down the vertical line from the waistline to your pivot point.

Your pattern piece should be looking a little something like this:

Step 4

Slip a piece of scrap paper underneath your skirt back pattern. We can now begin the process of spreading the pattern to create that added space we need in the butt area.

Taking ahold of the top of the centre back seam, gently pull up and out to open up the pattern piece. When you've spread the skirt out by an 1" (or by however much you need to increase your hip measurement by), you'll see that in doing this, you will have increased the hip measurement and the centre back length (to allow for a more exaggerated curve at the derrière), all the while keeping the side seam and hem the same. 

When you're happy, tape it down.

Step 6

To keep the waistline the same, we simply need to draw in a dart - draw the dart point about 4 1/2" down from the waist, and then draw dart legs to connect this point with the openings at the waist. Once you've sewn up your next toile, you can tweak the dart on your body in case it needs to be longer or shorter.

Redraw the centre back seam by continuing the wider top left section down to the hem:

Cut your skirt back piece out and you're done!

And there you have it! With all alterations, we highly recommend that you make another toile to check that you're happy with the alterations that you made before cutting into your delicious fashion fabric! 

Comments on this post (1)

  • Dec 02, 2019

    Thanks for this tutorial. I have a question though, is this adjustment interchangeable with the one for the Kim dress, or are they used depending on whether or not the skirt pattern has a dart?

    Many thanks.

    — Tonya

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