slopermain image3 How To Draft A Sleeve Sloper: Update

Assuming that you used my tutorials on how to draft a front and back bodice sloper, then you’re ready to draft the sleeves.

Sleeves are tricky. In my opinion, a sleeve’s difficulty lies in the fact that a 2D, flat piece of fabric is being made to fit a 3D, rounded object – the armhole. It’s the same difficulty a painter experiences when making a 2D canvas look 3D. Although difficult, it is completely possible. While painters use perspective to make a painting look 3D, seamstresses use basting stitches and ease to make a sleeve fit an armhole.

There are many factors that affect the fit of a sleeve – sleeve cap height, sleeve cap width, and the relationship of the front sleeve cap to the back sleeve cap are just three. But the most important factor that affects the fit of a sleeve is sleeve cap ease. Sleeve cap ease is the extra amount (or length) that is given to the sleeve cap so that it fits over and around the shoulder joint. Sleeve cap ease also effects sleeve cap height, sleeve cap width, and the shapes of the front and back sleeve caps (example: increasing the amount of sleeve cap ease will and/or increase sleeve cap height and sleeve cap width). The secret to sleeve cap ease is that it depends. More simply stated, the correct amount of sleeve cap ease for a particular garment depends on its fabric and its silhouette. This is where textbooks go wrong. Many textbooks advise that all sleeve caps should measure between 1” and 1 1/2” more than the sum of the front and back armhole. In some cases, this amount of sleeve cap ease works (tailored jackets) but in most cases, it does not. For two and a half years, I worked in the technical design department for this company and shortly after I started (I was fresh out of college), I was shocked when I was asked to measure the length of the sleeve cap and the front/back armhole – the sleeve cap only measured ½” more than the front/back armhole. But it worked! It was a knit t-shirt and for this style and silhouette, that amount of eases was okay (on a knit t-shirt, the sleeve cap doesn’t “lift” as it does in a woven – it lays close to the body). After working on too many sleeves over the course of two and a half years (I changed departments since – I blog for the company now), I defined my own rule – it depends. Some sleeves will require little ease (1/2″-3/4″ for knits) while some sleeves require a lot of ease (1 1/2″-1 1/2″ for tailored jackets) and this is because some fabrics ease easily (knits) while others do not (suedes/leather) and some silhouettes require more ease (tailored jackets) while others do not (drop shoulder). Make sense?

In the diagrams and directions below, I will show you how to draft a sleeve for the silhouette and the fabric that is most commonly used for a sloper – a standard set in sleeve using muslin. When you manipulate the bodice pattern to create other designs, you will have to alter the sleeve cap (including ease) to fit that particular design (I posted how to change sleeve cap ease here).

Before I start with measuring and drafting, below are a few other points on sleeves. This will help you understand why my sleeve is drafted the way it is as well as make you more knowledgeable on sleeves.

Just like sleeve cap ease, the amount of ease for the bicep depends on the fabric and the silhouette. Some biceps require more ease (1″ on a short sleeve woven blouse and a sloper) while other require little ease (3/8″ on a knit).

Sleeves should pitch slightly forward. Why? Stand sideways in front of a mirror and let your arms hang freely. You will see that from shoulder to elbow, your arm pitches forward only slightly but from elbow to wrist, your arm pitches forward more. Since this is the way the arm hangs naturally, so too should the sleeve. The placement of the shoulder notch affects the pitch of the sleeve and if the sleeve is pitching incorrectly, the shoulder notch is moved forwards or backwards accordingly.

The shape of an armhole is an asymmetrical horseshoe with a flattened bottom (where the side seam meets the armhole).  This is why armholes on front and back bodice should intersect side seam at a ninety degree angle.

The shape of the front and back sleeve cap is different. The front sleeve cap is more shaped and sits more forward (just slightly) than the back sleeve cap. This is because the ball of the shoulder, a very rounded shape, sits at the front of the arm.

The closer the armhole fits to the body, the more shaped the armhole is on a pattern and the more mobility the sleeve will have. This may not make sense at first but think of an oversize or dropped shoulder silhouette. On such a style, the armhole is less shaped and therefore does not move with the arm as well. When the arm is raised in  an oversized or a dropped shoulder, the underarm “wedges” out. Initially, a pattern maker may want to reduce the bust width at the side seam but all that is needed is to add more shape near the bottom of the armhole.

slv measurements How To Draft A Sleeve Sloper: Update

Okay, now let’s get started…

Using the diagram, measure the following:

{OVERARM LENGTH} measure from shoulder tip (¼” from the end of shoulder. If you start to raise your arm, a hollow will form at the shoulder joint. This is shoulder tip – approximately) to ½” past wrist bone. Be sure to measure with arm slightly bent or else sleeve will appear too short when fully bent or too long when fully relaxed
(ELBOW LENGTH} shoulder tip to bone at elbow
(BICEP} measure around the arm and ensure measuring tape is level with the armhole depth/armpit (click here to find armhole depth/armpit). Add  1” to this measurement (for ease)
(WRIST} measure around the widest part of the hand
(SLEEVE CAP HEIGHT} – use diagram above to determine sleeve cap height for your size

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A-B = Overarm length

A-C = Sleeve cap height

A-D = Elbow length

Square out lines to left and to right from points C, D, and B (doesn’t matter how long; just make sure each line is at least 1” longer than ½ of appropriate measurement)

C-E = half of bicep (make sure this measurement includes 1” for ease)

C-F = C-E (other half of bicep - make sure this measurement includes 1” for ease)

B-G = half of wrist measurement

B-H = B-G

Connect points G and E and points H and F

Label elbow level I and J as on diagram

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E-K = ¼ of E-C

F-L = E-K

A-M = E-K

A-N = E-K

Square up or down from the following points as follows:

K = square up 7/8” and label O
M = square down 5/8” and label P
N = square down 3/8” and label Q
L = square up 5/8” and label R

With straight ruler touching points O-P and Q-R, mark midpoints and label S and T as diagram

With a curved ruler touching points A, Q, and T and pointing down, draw top of front sleeve cap
With curved ruler touching points F, R, and T and pointing up, draw bottom of front sleeve cap
Repeat the last two steps to draw back sleeve cap

Honestly speaking, I was not happy with the shape of my sleeve cap at this point. Because my bicep is so small, my sleeve cap looked too narrow and tall. So I ask that you do the same as I. Look at the shape of your sleeve cap and compare it to the one in the diagram. Does it have a similar shape? As written above, the shape of the front and the back sleeve cap is different. The front sleeve cap is more shaped and sits more forward (just slightly) than the back sleeve cap. Does your sleeve cap do this? If it does not, use your instinct at redraw what looks like a correct shape. Doing so may increase or decrease the amount of ease on the sleeve cap (making a line more curved increases line length; making a line less curved decreases line length) but don’t worry about that right now. Let’s get the shape looking right and then we will adjust the sleeve cap ease. 

sloper31 How To Draft A Sleeve Sloper: Update


I-U = ½ I-D

U-V = 3/8” squared down from U

I-W = 1” (dart intake)

Connect points I and V and V and W

G-X = 5/8” (on wrist guideline)

H-Z = 5/8” (on wrist guideline)

Connect points W and X – extend line past point X  1” to compensate for dart intake

Connect point Y and Z

Connect points Z and J

Redraw front sleeve and ensure line transition smoothly from point F to point Z

Mark back sleeve cap notches with 2 lines (spaced ½” apart) with upper line 1 1/8” below point S (back sleeve always has 2 notches)

Mark front sleeve cap notches with 1 line that is 1” below point T (front sleeve cap always has 1 notch)

Lastly, let’s deal with sleeve cap ease. Because of the silhouette (standard set-in sleeve), the fabric (muslin/cotton), and the function of a sloper (fitted with only enough wiggle room to move), 3/4″ ease is a good amount of ease. So, if you measure the front armhole, the back armholes, and the sleeve cap, does your sleeve cap measure 3/4″ more than front and back armhole combined? Also, is the ease evenly distributed between front and back armhole, meaning is there 3/8″ ease on front sleeve cap (point A to point F along curve) and 3/8″ ease on back sleeve cap (point A to point E along curve)? If not, use this tutorial to change the amount of sleeve cap ease.

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