This gathered elastic hem technique will work for sleeves and pants.
Here I added elastic to the sleeves of my Sasha tunic.
Gather your supplies.
-elastic: 1/2″, 3/8″, OR 1/4″
-ruler, sewing gauge, measuring gauge, or other way to measure your hem
-completed but unhemmed shirt, bodice, pants, etc.
Your elastic needs to be 1/4″ narrower than your folded up hem. You have two options to determine which width of elastic to use.
1: Look at the hem allowance for the pattern and subtract 1/4″. (so you would use 1/4″ elastic for a 1/2″ hem)
2: Extend the sleeve so the hem allowance is longer. So if you want to use 1/2″ elastic, add an extra 1/4″ to the sleeve when you cut it. Then make sure you include that extra 1/4″ when you fold the hem up. (so your 1/2″ hem would become 3/4″).
I used 1/2″ elastic so I made the sleeve and hem slightly longer.
The first thing you need to do is measure around your arm with the elastic. I measured just below my elbow since I’m making a 3/4 sleeve. Hold it snug, but do not pull on the elastic. Include a small amount of overlap when you cut it so you can sew the elastic into a loop.
Cut a second equal length of elastic for the other sleeve.
Put a pin roughly 1″ from both sides of the seam and sew the hem down to create the elastic casing, leaving the 2″ around the seam open.
Pull the elastic through the casing, pin the ends together, and then sew them down.
Push the elastic loop inside the hem and sew the 2″ opening closed. Now you have a nice gathered elastic hem.
Repeat for the other sleeve.