I’m going to show you how to insert a sleeve into an armhole using a classic method which adds fullness at the shoulder. I'm going to demonstrate on the Mathilde blouse sewing pattern - you can use the same method on many other sewing projects.
The reason we’re adding fullness at the shoulder is to help the fabric curve over your shoulder where it sticks out from your body. A sleeve head is often at least 2cm (3/4in) bigger than the armhole - on the Mathilde blouse it's even bigger to create more visible gathering as a design detail. This excess fabric is gathered in so the circumference of the sleeve head and armhole match when sewn together, creating volume in the fabric to accommodate your shoulder.
In case you’re interested, not all sleeves are inserted this way. Some sleeve heads don’t have any ease at all. An alternative method - often used in shirt-making and on jersey t-shirts - is to insert sleeves “on the flat”, in other words, stitched flat against the armhole before the bodice side seam and sleeve underarm sleeve are joined.
Anyway, that’s the theory over – let’s get on with the sewing!
While the sleeves are still flat, we're going to start by adding gather stitchers (or "ease stitches" if the sleeve is less gathered) on the head. Thread up your machine in a contrasting colour so it’ll be easy to identify and rip out the gather stitching later (it’s only temporary), and set the stitch length to 4mm.
Stitch three rows parallel to each other on the top of each sleeve. Your pattern will have either gather markings or notches showing you where to start and finish the stitching. I usually sew my first row 5mm (1/4in) from the raw edge, and then each subsequent row 7mm (1/4in) from the previous one. That way they don't overlap the seam line 15mm (5/8in) from the edge, so they're easier to unpick later. Don't back tack, and leave a few inches of thread at each end so you have something to pull on when it comes to gathering.
Stitch the sleeve underarm seams, finish and press. On the Mathilde blouse you can use French seams here if you like.
Now we’re going to align the sleeve and armhole. The way to check you’re putting the correct sleeve into its corresponding armhole is to look at the little notches you cut from your pattern (if you don’t know what I’m talking about, check the pattern again). The front of the sleeve and armhole will have single notches; the back will have double notches.
Align the sleeve and armhole, with the fabric right sides together. This can be a little confusing the first time you do it, but really all you need to do is hold the sleeve right sides out and turn the garment wrong side out on top of it so the right sides are matching. Then line up the two raw edges of the sleeve and armhole seams.
Pin the sleeve and armhole together - with the pins at right angles from the raw edge and the heads sticking out - at the following points:
- Where the sleeve underarm seam meets the bodice side seam
- Shoulder seam and central point on sleeve
- Sleeve and armhole notches (those single and double snips we were talking about earlier)
- Below the gather stitches (don't pin on top of the gather stitches just yet)
Pull on the gather stitches – gently tug on a trio of threads to bunch up the fabric. Keep doing this until the sleeve fits into the armhole, smoothing out the gathering as you go to spread it nice and evenly.
Now stick as many pins in as you think you’ll need to help keep the gathers even. (Lots is good.)
If you’re super confident you can go right ahead and stitch. It’s a reeeeally good idea to tack (baste) first though to check you’re happy with your gathering. Tacking basically means sewing a practice run with long stitches (4mm) which are easy to rip out if you want to try again. Thread up your machine in a contrast colour so you can see the stitching easily and thus whip them out quickly. Tack just within the seam allowance - about 12mm (1/2in) from the edge - so your real stitches don’t end up directly on top.
When stitching, start at the underarm seam. Sew nice and slowly over the gathers so you can keep them evenly in place as you go. Come full circle to meet your starting point, making a couple of overlapping stitches to secure. The aim is to end up with even easing or gathering, with no pleats or puckers. If you need more help with sewing in sleeves, you can watch a detailed video on our online workshop, Sew Your Own Shirt or Shirt Dress.
Once you’re happy with your tacking, rethread your machine in matching thread to your fabric, reset the stitch length to normal (2.2 - 2.4mm) and sew your real stitches. Now you can unpick your tacking and gathering stitches with a seam ripper.
All that’s left to do now is finish your seam with zigzag stitch or an overlocker, and press it. When pressing the armhole, turn the garment inside out and press along the seam. If you want to you can press the seam in towards the sleeve, but try not to press the shoulder area, otherwise you’ll lose the fullness you’ve created with your gathers.
PS. If you'd like to get more tips and watch an up-close-and-personal video of a sleeve being sewn in, sign up to our online workshop, Sew Your Own Shirt or Shirt Dress.