Welcome to the Slacks Pattern Instructions. Today I’m going to show you how to draft this pattern step by step. Before starting, it’s important to know that any pants pattern is a difficult pattern to get right. It took me between 5-10 prototypes to get the right fit, so don’t worry if the same happens to you. It might be frustrating but I promise you it’s worth it! You can draft slacks from the trousers foundation but in this post I’ll show you how to do it from scratch.
The first step of this Slacks Pattern Instructions is to take the measurements.The first step of this slacks pattern instructions is to look at what measurements are needed. Wear the normal underwear you’d wear under the slacks and be careful not to tighten the measuring tape too much. This pattern is just one of many prototypes, so don’t worry if the measurements are not super precise.
Measure the circumference of the thinest part of your torso, below the rib cage. I’ll show you how to modify the pattern for high-waisted and low-waisted pants later on.
Measure the circumference of the widest part of your lower body. This is normally the hips but your widest part can sit lower. If you want more precision, you can always measure the front and back hip arches separately (from side to side).
Measure the vertical line from the waist to how long you want your trousers to be. Best results are when you measure until your ankle bone. They can be made longer or shorter later on.
The hip depth is measured from where you measured your waist to where you measured your hips, on the side of your body.
To take this measurement you have to sit on a flat surface and measure from your natural waist (or where you measured it) to the flat surface. Measure it on the side of your body.
Measure from the front to back waist, going in between the legs following the crotch shape. This measurement is optional to check the pattern before prototyping.
With that we have all the required measurements, but there’s a couple of optional ones that will be handy to check there is enough ease for mobility around the thighs, knees and ankles:
Step number one is to build the structure of our slacks foundation. We start at the top left and mark 0.
Finish drawing the rectangle
Divide the structure: From the line 0-1 half way to 1-2 plus 1cm. The front is on the right and the back is on the left.
Once the main structure is ready, let’s draw the main lines that will define the shape of the trousers
Let’s start drawing the actual trousers. We’re going to start by shaping the crotch curve.
Back curve: Draw a curve from 13 that goes 5cm outside of 5, through 15 and to 17.
Front curve: Draw a curve from 14 that goes 3.75cm outside of 11, through 10 and to 18.
Next step is to draw the Waist. For that we’ll need to make some assumptions about darts.
Darts are our way to create rounder shapes in the pattern. Every body will need different measurements. The rules are:
As a standard dart measurement you can use:
As explained before, darts will depend on your body. This is the standard way of drawing them but use the ones that suit you best.
The dart on the back is 12cm long and the one on the front is 7.5cm long.
To define the leg lines, we need to find the crease line. That is the line that divides the trouser legs in the middle.
Draw a line perpendicular to the crotch line. From there we can draw the width of the slacks at knee and hem lines:
Back Curve: Draw a curve from 13 to the knee and hem lines for the inseam. For the side seam go 0.5cm inwards at point 8.
Front Curve: Draw a curve from 14 to the knee and hem lines for the inseam. For the side seam go 0.5cm inwards at point 8.
And there you go, you have your trouser foundation pattern! There are a couple of checks you can do to make sure the fit will be good enough:
If you prefer step by step instructions in a video format, check out the following video. Take into account that the correct numbers are ALWAYS the ones on this article and not the ones on the video, as it is difficult to correct errors once the video has been published.
Once you have this foundation, it’s time to play around and change the waist line, add a waistband, add volume, change the leg-line or add details.
If you want to know more about how to modify the foundations check the trousers 101 page or take a look at the free pattern instructions.
If you tried my method and liked it, think about getting my ebook on how to draft trousers.
In there you’ll find everything you need to know to draft any design you’ve ever dreamed of.
Head to my shop by clicking the image on the right and get it now!
