Set-In Sleeves: How do they work?

I'm always amazed when I set in a sleeve cap and it works out. I never think it will, but it usually does. I guess my mind doesn't bend in the same sort of curves that a set-in sleeve does!

The Refined Aran Cardigan by Pam Allen. Download your free pattern now!

How does it work? Pam Allen, the designer of one of my favorite (and free!) cardigan knitting patterns—the Refined Aran Cardigan—is here to tell us how.

Sleeve Caps: A Love Affair

There was a time when I was baffled by the construction of sleeve caps. Although I would leap into a sweater design with gusto, knitting the back, front, and sleeves to the armhole lickety-split, I found myself faltering at the prospect of working the cap. It was fudging on a major scale—a matter of gritting my teeth, closing my eyes, and knitting a series of decreasing rows till I had what seemed an appropriate shape. The telling moment, of course, was when I tried to match the upside-down U of my cap into the round armhole opening of my garment. Would it fit? Maybe with a few more rows? A few less?

I've spent a lot of time learning-through more trial and error in the wee hours than I care to remember-how to design a fitted sleeve and its cap. There are standard formulas, true, but I've never been a fan of the one-formula-fits-all approach. The way a sleeve fits and the construction of the cap contributes more to the look and feel of a garment than we generally credit. We all recognize a 1940s jacket or sweater by its long, narrow sleeve cap and squared shoulder. And the high, tight armhole and narrow-shouldered silhouette of a poor-boy sweater date it indelibly from the 1960s. Understanding how the symbiotic trio of armhole, sleeve, and sleeve cap contribute to the look of a garment and, more importantly, how they relate to each other is all-important in sweater design.

Although it's possible to knit up a sleeve by tinkering this way and that, it's far more satisfying to be able to plan a cap that will fit perfectly into its armhole from the get-go. And to do that, you need to understand how sleeves, caps, and armholes relate to each other.


THE TRIO: ARMHOLE, SLEEVE, AND CAP Picture first the curved edge of a garment's armhole, starting from the initial armhole bind off, curving up to the shoulder and down the opposite side (Figure 1A). The measurement of this curve is a fixed entity. Now picture a sleeve cap. Although the shape of the cap doesn't correspond to the cutout of the armhole—these aren't puzzle pieces that fit together as positive and negative shapes—the actual line of the perimeter of the cap needs to measure the same, or slightly more than, the armhole edge to fit in neatly (Figure 1B). The perimeter of the cap consists of the bound-off stitches at the armhole, the bound-off stitches at the top of the cap and the curved and/or tapered sides between them.

Although you can design a cap that has a perimeter measurement equal to that of the armhole, and let the knitted fabric give over the curve of the arm at the shoulder, I like to add a little ease at the top of the cap to build in a little roundness for the arm. If the perimeter of the sleeve cap is too long, however—more than 2 inches—the sleeve cap, eased in, will pucker. If it's too small, the armhole of the garment will pucker, and the sleeve cap will be stretched along the armhole seam.

Now think about the lower part of the sleeve. The width of the sleeve at the upper arm is what determines the shape of the sleeve cap. Each of the caps in Figure 2 has the same perimeter, but each one is shaped differently to maintain the length of the perimeter. If we widen the sleeve, the cap must grow shorter and flatter. If we narrow the sleeve, the cap must be taller and narrower. You can test this yourself with a flexible tape measure.

Measure out 16 inches. If you hold both ends 12 inches apart (a narrow sleeve width) the curve mimicking the cap is tall and narrow. If, however, you spread the ends out to 14 inches, the curve of the tape measure flattens out and the height shrinks. Within those 16 inches of tape, whether the ends are 12 inches or 14 inches apart, you can adjust and play with the curve of the pretend cap. In real life, as long as the perimeter of the cap measures the same as that of the armhole, you can shape your cap in different ways—and each time, it will fit. Read more . . .

—Pam Allen, from Interweave Knits, Winter 2007

This sort of in-depth, expert information, is what you should expect from Interweave Knits. Get your subscription today; it'll make you a better knitter.


P.S. Do you have any tips for knitting set-in sleeves? Share them with us in the comments!

Other Things You May Like to Check Out:


Knitting Daily Blog
Kathleen Cubley

About Kathleen Cubley

Hello daily knitters! I'm the editor of Knitting Daily. I've been obsessed with knitting for about ten years now and my favorite projects are sweaters. I like the occasional smaller project, but there's nothing like yards of stockinette with a well-placed cable or a subtle stitch pattern here and there. I crochet a bit now and then—especially when I need to produce a baby blanket in time for the baby shower. I've been in publishing for 20 years and I'm finally exactly where I want to be: at the crossroads of knitting and communication. I live in Spokane, Washington and when I'm not knitting I enjoy gardening, snuggling with my dogs, swimming, reading, and playing in the snow in the winter. But, really, I'm pretty much always knitting!

11 thoughts on “Set-In Sleeves: How do they work?

  1. I make almost all sweaters with the same shoulder and sleeve-cap profile (raglans don’t look good on my sloping shoulders), making up my own pattern (though I sometimes copy stitch ideas). So I made a template out of pellon interfacing. I usually do the sleeves first (a kind of extended swatch — starting with a cuff, that tells me if the ribbing is the right look and the gauge is right, helps me practice centering patterns if necessary, etc.), and the template tells me when I have the right width at the top of the sleeve, then I follow the template as I’m shaping the sleeve cap. When I get to the front and back of the sweater, I use the same bind-off at the armscye, then I just need to knit the top long enough to go to the middle of the top of the sleeve cap. (The tricky bit is coordinating with neckline bind-offs or decreases).

  2. Very interesting article with the concepts well explained. One tip I have is to knit the sleeve into the armhole with a fair bit of ‘give’ to my stitches and then go over them again to cast off -that would be bind off for my American friends. I have also done the shaping with short rows instead of lots of little cast off steps. I then have live stitches with which to knit in said sleeve.


    Wendy Leigh-Bell

  3. Not a tip, but a question: Seaming! I have a cardigan completed and seamed–except for the set in sleeves. I just can’t get the seams to look professional. Side seams and shoulders–perfect. But the sleeves–AAGH! Any help for me?

  4. For the love of sanity, don’t try to seam set-in sleeves. Instead, either pick them up from the armhole and knit down, or do the simultaneous set-in sleeve thing. Once I stopped trying to seam caps, my sweaters looked a million times better. Several recent books on seamless construction now have instructions for both these things.

    @brenfinn, if you can handle the thought of frogging, I’d just redo the sleeves with one of these methods.

  5. It’s just 4 pages guys. I think maybe the 34 is the original place in the magazine, as yo can clearly see the article is over by the little square that shows up at the end of the article

  6. DeborahG@22 the method I was shown was to join the shoulder seam, lay the sweater out flat, right side up, set your sleeve down in the gap, begin at the top & go down each side with mattress stitch. It is easier if you pin a little. Center top, bottom, & ease as necessary Between with pins before starting to stitch. When the cap is in;sew the side seam from sleeve edge to bottom of sweater. Worked very well for me…hope it helps you.

  7. DeborahG@22 the method I was shown was to join the shoulder seam, lay the sweater out flat, right side up, set your sleeve down in the gap, begin at the top & go down each side with mattress stitch. It is easier if you pin a little. Center top, bottom, & ease as necessary Between with pins before starting to stitch. When the cap is in;sew the side seam from sleeve edge to bottom of sweater. Worked very well for me…hope it helps you.

  8. I would love it if you could do a discussion of how the top-down seamless set-in sleeve works. I have several patterns that use it, but I don’t *understand* it well enough to use it outside a pattern.

    And…I don’t sew up anything, so seamless is the only way I can make sweaters. 😉

  9. I have a question about the pattern for the Refined Aran jacket. I can’t seem to figure out the cap part either…it’s getting too long.

    “Dec 1 st each end of needle every other row 7 (8, 9, 8, 8) times, then every 4th row once, then every other row 4 (5, 6, 6, 7) times, then every row 8 (10, 10, 14, 16) times, ending with a WS row—14 sts rem; 12 chart sts plus 1 seam st on each side. ”

    is this really right?

    appreciate all the help I can get!

    / Jasmina