Welcome to the Jeans Pattern Instructions. Here you’ll be able to find a step by step guide on how to draft your first pair of jeans. Before you start, it’s very important to know that pants are one of the most difficult pattern to master. Normally it takes between 5-10 prototypes to get the perfect fit, so it’s okay to get frustrated. BUT, I promise you once you have the finished pattern, you’ll be able to draft any design you want, so let’s get into it!
Measurements
The first step of this jeans pattern instructions is to look at what measurements are needed. Make sure you write them down on a piece of paper. Make sure the tape is not too tight around your body. It’s also important to understand that it’s okay not to be super precise, as you’ll be able to modify the pattern during the prototyping phase.
WAIST CIRCUMFERENCE
Measure the circumference of the thinest part of your body. If you want to be more precise, you can measure the front and back waist curve instead of the whole circumference.
HIP CIRCUMFERENCE
Measure the circumference of the widest part of your body. If you want to be more precise, you can measure the front and back hip curve instead of the whole circumference.
TROUSERS LENGTH
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.
HIP DEPTH
Measure the vertical line from the waist until where you measured the hip circumference. This measurement is taken on the side.
CROTCH DEPTH
Sit down on a flat surface and measure the vertical line at the side of your body, from the waist until the flat surface.
CROTCH LENGTH
This measurement is used to check the pattern and is measured from your front waist and following the crotch area until the back waist.
These are all the basic measurements needed for the jeans pattern instructions. There are a couple of other optional useful measurements:
- Upper thigh circumference: This measurement is very useful to check the allowance around your upper thigh. It’s measured around the top part of your leg just below the crotch
- Knee circumference: This measurement is to make sure there is enough ease around the knee to allow for mobility. It’s measured around the widest part of your knee
- Ankle circumference: This measurement follows the same purpose as the last two and it’s measured around the widest part of your ankle bone
Instructions
Step 1 – Structure
Step number one is to build the structure of our slacks foundation. We start at the top left and mark 0.
- 0 – 1: Trousers length measurement
- 1 – 2: Half the hip circumference plus 0.5cm
- Finish drawing the rectangle
- Divide the structure: From the line 0-1 half way to 1-2 plus 1.5cm. The front is on the right and the back is on the left.
Step 2 – Main Lines
Once the main structure is ready, let’s draw the main lines that will define the shape of the trousers
- The line 0 – 3 is the Waist Line
- 0 – 4: Waist to hip measurement. This is the Hip Line. Mark 4,7 and 10
- 0 – 5: Crotch depth. This is the Crotch Line. Mark 5, 8 and 11
- The line 1 – 2 is the Ankle Line
- 1 – 6: Half the distance between the crotch line and ankle line + 2.5cm. This is the Knee Line. Mark 6, 9 and 12.
Step 3 – Crotch Curve
Let’s start drawing the actual jeans. We’re going to start by shaping the crotch curve.
- 5 – 13: 1/4 of the distance between 5 and 8. This is the back crotch extension.
- 11 – 14: 5cm. This is the front crotch extension
- 0 – 15: Half way between 0 and 5.
- 3 – 16: Half way between 3 and 11 minus 1.25cm
- 0 – 17: 4.5cm to the right and 2.5cm up
- 3 – 18: 1.25cm to the left and 0.5cm up
- Back curve: Draw a curve from 13 that goes 4.5cm outside of 5, through 15 and to 17.
- Front curve: Draw a curve from 14 that goes 3cm outside of 11, through 16 and to 18.
Step 4 – Waist
Next step is to draw the Waist. For that we’ll need to make some assumptions about darts.
- 17 – 19: 1/4 of the waist circumference + dart measurement + 0.5 cm ease (optional)
- 18 – 20: 1/4 of the waist circumference + dart measurement + 0.5 cm ease (optional)
Darts are our way to create rounder shapes in the pattern. Every body will need different measurements. The rules are:
- Darts should be maximum 3 cm wide. After that they should be divided by 2.
- 2 darts are used for larger hips/small waist and 1 dart for more rectangular bodies.
- The same stands for the belly
As a standard dart measurement you can use:
- Front: 1 dart of 1cm.
- Back: 1 dart of 2cm.
Step 5 – Darts
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.
- On the back side (left on the drawing) we’ll draw 1 dart of 2cm. It is placed half way between 17 and 19.
- On the front side (right on the drawing) we’ll draw 1 dart of 1cm. It is placed 8cm to the left of 18.
The dart on the back is 9cm long and the one on the front is 6.5cm long.
Step 6 – Leg lines
To define the leg lines, we need to find the crease line. That is the line that divides the trouser legs in the middle.
- 8 – back crease-line: Half the distance 8 – 13 plus 1cm
- 8 – front crease-line: Half the distance 8 – 14 plus 1cm
Draw a line perpendicular to the crotch line. From there we can draw the width of the trouser hem:
- Back: 10cm on each side
- Front: 9cm
These measurements are standard and can variate depending on the desired width. Normally the back width is bigger than the front one. In the image you can see I also add some standard measurements for the knees. This is not completely necessary but it gives more of a slim version.
Step 7 – The Jeans
Now you have all the points to draft the trousers.
- Back: Draw a curve from 19 to 7 and then to your ankle width. For the inside of the leg draw a line from 13 with an inward curve to the ankle width.
- Front: Draw a curve from 20 to 7 and then to your ankle width. For the inside of the leg draw a line from 14 with an inward curve to the ankle width.
The jeans should follow the shape of your body, that’s why you should draw the leg-line 1cm inwards from point 8 on both sides instead of a straight line. The crease-line we drew in step 6 already takes this into account.
And there you go, you have followed the jeans pattern instructions till the end! There are a couple of checks you can do to make sure the fit will be good enough:
- Check the upper thigh, knee and ankle circumferences and compare them to your pattern. The pattern should always be bigger than the real measurements.
- Compare the crotch length in the pattern and the real measurement. The pattern should be the same or longer than the actual length.
- Measure the side seam for both front and back patterns. They should be the same measurement.
Thank you for using this Slacks Pattern Instructions. For more information on how to modify this pattern, click here
I also made a video with all these explanations:
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