What is a Flat Pattern?

A flat pattern is like a blueprint for cutting your fabric. It translates the flat, 2-dimensional
fabric, to fit around a 3-dimensional body while allowing for both the proper aesthetic fit as
well as the proper fit for the comfort and range of motion for the wearer.

Flat patterns can be drafted “from scratch” or by starting with a basic pattern and
manipulating it to look how you want. We’ll discuss pattern manipulations in a
separate article, but in this post we will draft from scratch.

What Do We Need to Start Drafting?

 Body measurements for the size we are creating

If you are drafting your pattern on paper, you will also need:

 Pattern Paper
 A pencil
 A French curve
 A straight ruler
Pattern making tools

Or, you can draft on the computer using a CAD program. We used Gerber Accumark,
so that is what you will see reference in some of the images, but other common
programs are Optitex and Lectra.
Depending on how and why you’re creating a pattern, and if you’re doing so for
yourself, a small business, or a larger corporation, you will have a different reference
for what your style looks like. This could be a reference image of an existing garment,
the reference garment itself, a stylized sketch, or a tech pack complete with technical
drawings.
Cover page of tech pack created using Techpacker

We will be using a tech pack, with a technical sketch, for this simple sweatpant with
an elasticated waistband and leg cuffs.

For our purposes, we will be using the following body measurement chart. (ASTM
standard body measurements from Patternmaking for Fashion Design, 4th Edition.
Helen Joseph-Armstrong)

POINT OF MEASUREMENTS MEASUREMENTS (IN INCHES)

Waist 27 ½”

High Hip 36”

Full Hip 39”

CF Crotch Depth 10 ¼”

CF Hip Depth 9 ½”

Side Hip Depth 9”

Waist to Ankle 38 ½”

Total Rise 26 ¾”
 POINT OF MEASUREMENTS MEASUREMENTS (IN INCHES)

Waist to Knee 23 3/8”

Thigh 22”

Knee 14 ½”

Ankle 10 ¼”

When drafting patterns, you will typically be working sideways, as this is

To start with, we will draw some baselines. The first will be our side baseline. This will
be equal to our waist to ankle measurement of 38 ½” and you will draw this line
horizontally on your screen or paper.

Side baseline 

Next, we will at our waist baseline at the top of our side baseline. The full waist
circumference in 27 ½”, but we are currently working only on half of the body, so we
need a waist baseline of 13 ¾” and we will center this on our side baseline.
Waist baseline 

At the CF, we have a hip depth of 9”, so we will draw our hip baseline 9” below our
waist, again this should be half of the body measurement and centered on the side
baseline. We will also add our crotch baseline at 10 ¼” below the waist. For now, we
will keep our crotch line the same length as the hip line.

Hip-crotch baseline

Similarly, we will add our knee baseline 23 3/8” below the waist (as indicated by our
waist to knee measurement), and our ankle measurement at the bottom of our side
baseline. Both of these lines will be centered on the sideline, but unlike our torso
measurements, they will not be halved as they are the leg circumference.
Knee-ankle baseline

We will use these baselines as a sort of skeleton for our pattern, as they are mapping
the body for us.

Now we need to start adding in shaping and ease to create our garment pattern.
Let’s start with the rise curves. The ease amounts I will include here are based on
standard ease amounts for the type of garment we’re creating and will vary based on
the garment type and fit.

Our garment is going to sit 1.5” below the waist, so we will add a line 1.5” below our
waist baseline which will be the “garment waistline” and for now, it will be the same
length as our hip line, at 19.5”. We will also draw a small line that is ½” tall ¼” away
from the back edge of our new garment waistline.
Back waist point

Now, we need to extend the back crotch, as it will be wider than the hip to create our
rise curve. There is a bit of math involved here. Right now, our crotch baseline is 19.5”
(equal to our half hip) with 9.75” to the front, and 9.75” to the back.

For our back crotch extension, we will take that 9.75” and extend the crotch by half
that, or 4.88”. For the front crotch extension, we will extend by ¼ of the 9.75”, or
2.44”

We also need to add some ease to our crotch point so it doesn’t dig in on the
wearer, so we will shift the crotch line down by 1”. If you are doing this on paper,
simply draw a new line 1” lower and cross our or erase your crotch baseline.
Crotch extension

Our crotch line is currently 11.25” below our waist baseline. We need to add a new
line halfway between, at 5.63” as this will be important to creating a balanced rise.
Label this new line “midline” so that you don’t get it mixed up with your hip baseline
or garment waistline.

You will also draw a line straight down from each end of the midline to the crotch
line, creating a box.

Midline
You have created right angles at the front and back now, where the crotch line and
the new lines you just drew connecting the midline meet each other. At the back
crotch, you will draw a 2” line at a 45 degree angle coming from this right angle and
at the front, you will draw a 1.5” line at a 45 degree angle.

45 degree

Now, we will play a bit of connect the dots to create our rise curves.

For the back rise, draw a curve from the end of the crotch extension to the end of the
2” line we just created. Then draw a curve from that line up to the end of the midline.
You will then draw a straight, slightly diagonal, line connecting from there to the little
back waist point we created earlier.
Back rise curve 

For the front rise, we will do the same thing, except that you will just have a straight
line from the midline to the garment waistline.

Front rise curve

Congrats! You made it through the most complex part of pant drafting – the
bifurcated crotch.

Ok, let’s get the last few parts of our pattern done.
We are using a stretch fabric and want these to be a slim fit at the hip, so we will not
add any wearing ease at the hip. We will be adding elastic to bring in the waist, but
we want to narrow it a bit now to create a nice fit at the hip. We want our garment
waist to be 2” narrower in total circumference. That means we need to take out 1” on
our half body piece, and ½” each from the front and back. We will add notches ½”
on either side of our side baseline on the garment waistline.

Waist notches 

And now we will add a curved line from each of these notches to where the hip and
side baselines meet. This will be your hip curve.
Hip curve

Let’s give our waistline some shape so it fits the body nicely. We will make a notch
½” below the top of the front rise. Draw a slightly curved line from that notch to the
top of the front hip curve. Draw another slightly curved line from the top of the back
hip curve to the top of the back rise.

Garment waistline

Can you start to see your garment taking shape?

Knee and ankle extension

Now we will draw our front and back inseam lines by connecting the front rise to the
front knee and then the front knee to the front ankle. We will repeat this at the back.
To ensure that your garment sews together smoothly, you want to make sure that
both the front and back crotch points create a 90 degree angle with the inseam for at
least the top ½” of the line.
Inseams

You’ll see that the top of the front inseam is a bit more curved than that back, this is
to help the inseam lengths match each other, as they will be sewn together later.

Ok, so now we’re almost done!

We are going to have a 2” tall waistband and 2” tall leg cuffs. So we need to draw a
second waistline 2” below the existing garment waistline and new pant hem line 2”
above the ankle line. These lines should be parallel with the existing lines. I’ve gone
ahead and deleted a lot of my baselines in this image to make it easier to see, but
yours will still have them.
WB and cuff offset lines 

Now we will trace our front and back leg pieces to separate them. Make sure that
you’re tracing using the newly added lines for the waist and hem.

Back leg traced

Now we just need to create our leg cuffs and waistband, which will be made with
simple rectangles.

The cuffs will measure smaller than the leg opening and need to be eased in while
sewing. Since we know that our body measurement for the ankle is 10 ¼” and we
want the cuff to have negative ease to sit snugly, we will make our cuffs 9 ½” long.
We have a 2” tall cuff, but its folded in half, so we need to make it 4” tall.

For our waistband, we will make it 1:1 with the waistline seam and use elastic to bring
it in. our waistline seam on the half measures 18.8” so we need to make our
waistband 37.6” long. It will also be 4” tall like our cuffs.
WB and cuff

Now, we just need to add seam allowance. The amount may vary slightly depending
on the supplier or fabric, but most times for overlocked seams the seam allowance
will be 3/8” or 1cm so that’s what we will add to all pieces.

Seam allowance 

You would also want to add notches, mark the drawcord exit placement, etc. to make
your pattern production ready. You can learn more about that in our Apparel Pattern
Making Guide below.