Whether you’re a beginner or an experienced sewer, sleeves can be a little intimidating—whose idea was it to try and fit a rounded curve into an armhole anyway?
No matter what type of garment you’re creating—from coat to T-shirt—you’ll likely be facing one of two types of sleeves: either one with a rounded cap or one with a flat cap. (Raglan is another type of sleeve, but requires a different insertion method.)
Rounded caps are found in more tailored and fitted garments and are commonly called set-in sleeves, while flat caps (aka shirt sleeves) are found in more sporty garments, menswear and kids’ clothes, and getting them into your garment requires different strategies.
Set-in Sleeves
The shape of a rounded sleeve cap allows for ease to fit over the shoulder curve and upper arm area. If you measure the seamline of the garment and you measure the seamline of the upper sleeve, you’ll find that the sleeve is longer. That means you’ll need to ease the fullness into the smaller garment opening.
A rounded sleeve cap has important pattern markings—at the shoulder and part way along the sleeve cap both front and back, including placement notches. These are key for distributing the ease.

The area below the armhole notches on the sleeve should fit the armhole itself with no ease, as the ease area is concentrated at the top portion of the sleeve, above the notches.
To evenly distribute the sleeve cap ease, stitch a line of basting length stitches 1/8” inside and outside the seamline from notch to notch—do not backstitch, but instead leave the thread tails long enough to pull.

The first step in insertion is to sew the underarm sleeve seam and the corresponding garment shoulder and underarm seam, and press both open. With right sides together, place the sleeve inside the armhole opening and pin at the notches, seamline, shoulder point and corresponding markings on the cap. Gently pull on the bobbin threads of the ease line to fit the sleeve to the armhole size, working from the notch area to the shoulder.
If your machine has a free-arm, this is the place to use it, as the sleeve opening can fit over it for easier access.
Beginning at the underarm seam, stitch the sleeve in place adjusting the ease as needed to fit and being careful to avoid any puckers. Sew with the sleeve side up to control the ease.
Reinforce the lower armhole with a second line of stitching ¼” inside the seamline. Trim the seam allowances below the notches, but leave the seam allowances intact in the cap area to fill out the sleeve head. Push the upper sleeve seam allowances toward the sleeve, but don’t press this area as it will flatten, eliminating the ease you just carefully created. Remove any visible basting.
If you’re working on a tailored garment with a two-piece sleeve, follow the pattern guidesheet to sew the undersleeve to the top sleeve before inserting it into the garment.
Flat Sleeve Insertion
Shirt sleeves have the same markings as their set-in cousins—notches front and back, a shoulder marking and often some intermediate marks as well. This type of sleeve is put in prior to sewing the garment side seams and sleeve underarm seam. No ease line is necessary for this type of sleeve—simply match the notches and other marks, right sides together, and stitch with the sleeve side up.

Shirt sleeves can easily be inserted with a serger or conventional machine. If you choose the latter, sew a second line of stitching, either zigzag or straight just inside the seamline and trim off the extra seam allowance.
With right sides together, match the garment underarm seams, hemline and sleeve hem, then sew the seam continuously. Finish and trim as for the sleeve cap area.

All images provided courtesy of Bernina
~Linda Griepentrog is the owner of G Wiz Creative Services and she does writing, editing and designing for companies in the sewing, crafting and quilting industries. In addition, she escorts fabric shopping tours to Hong Kong. She lives at the Oregon Coast with her husband Keith, and three dogs, Yohnuh, Abby, and Lizzie. Contact her at gwizdesigns@aol.com.




























