Thumbhole cuffs are a fun and practical way to keep your hands a bit warmer during those chilly months. You can add a thumbhole cuff to pretty much any sleeve you choose. For example, my kiddo and I here rocking ours with our Alpine Sweatshirts.
Generally speaking, you'll cut your sleeve using the normal hemline. You can shorten the sleeve slightly if you want to avoid the wrinkling at the wrist, but keep in mind the cuff needs to be able to go over your thumb. You want the cuff to start at your wrist bone or just below.
If your pattern already comes with a long sleeve cuff, great! You can modify it easily by adding to the height to make 8.75" (22.2cm) high. If not, you'll need to come up with how tight you want the cuff to be. Below is a general example of cuff dimensions. If you are making a relaxed sweatshirt, you may want to add 1/2 to 3/4 of an inch or so to the width. If you are making a fitted garment, you may want to subtract a half inch.
Measurements are given as Length (with the grainline) by Width (with the stretch/crossgrain).
Ok! Now that we've got our sleeves and cuffs, let's get this show on the road. If you'd like to follow along with me in video form, be sure to check out our YouTube Thumbhole Cuff Tutorial.
1) FIRST take care that you know which way the stretch of the cuff is and which way the grainline is. Especially in the smaller sizes, this may not be obvious.
Fold the cuff lengthwise across the stretch of the fabric RST. Mark the fold line with chalk. Unfold.
Fold the cuff the opposite way next, with the grainline, RST.
Measure up 1" (2.5cm) and 1" (2.5cm) down from the center fold mark and place a pin at each point (2 and 3).
Measure 2" (5cm) and 2" (5cm) down from points 2 and 3. Place a pin at each point (1 and 4).
That will leave you with 1.375" (3.5cm) at the top and bottom of the cuff.
Mark with pen or chalk each point on both sides of the cuff so you can use them to match in the next steps (pins get in the way).
Using your regular machine with a stretch stitch (lightning bolt, triple stretch or narrow zig zag), stitch from point 2 to point 3.
Make sure you backstitch or tack the stitches at either end.
Fold down one side at both corners and across seam allowance.
Fold the entire cuff in half along your original chalk marked line, being sure to keep the seam allowance and both corners out of the way.
Match point 3 to point 2 and point 4 to point 1.
Place pins at the 1 and 4 match point and the 2 and 3 match point. Match the raw edges between the pins. Ensure you are keeping all other fabric out of the way so nothing gets caught in your stitches.
Sew between the pins using the same stretch stitch as before. Sew as close as possible to your previous stitches. You want to touch them, but not go past them. Make sure to backstitch or tack at each end.
Turn the cuff right sides out and then wrong sides out the OTHER way so that you can match up your other set of marks/pins.
Just like before in step 6, match point 3 to point 2 and point 4 to point 1.
Place pins at the 1 and 4 match point and the 2 and 3 match point. Match the raw edges between the pins. Ensure you are keeping all other fabric out of the way so nothing gets caught in your stitches.
Sew between your pins using the same stretch stitch as before. Sew as close as possible to your previous stitches. You want to touch them, but not go past them. Make sure to backstitch or tack at each end.
Turn the entire cuff wrong sides out. It's going to look a little bit odd, sort of like a fortune cookie.
You have two more seams to sew. Match the raw edges. Match point 4 to point 4 and match point 1 to point 1. You'll have to manipulate all the extra fabric out of the way so that you don't catch your stitches.
Sew between your pins using the same stretch stitch as before. Sew as close as possible to your previous stitches. You want to touch them, but not go past them. Make sure to backstitch or tack at each end.
Quarter and pin both cuffs.
Quarter and pin both sleeve openings.
With your top Right Sides Out, place your cuff around the long sleeve opening, lining up the raw edge of the sleeve opening with the raw edges of the cuff. Match and pin the quarter marks, aligning the cuff seam (thumbhole) to the under arm sleeve seam.
Stitch/serge the raw edges of the cuff to the raw edge of the sleeve opening.
Stretch the cuff to meet the sleeve opening in between the pins. Do NOT stretch the sleeve opening while sewing.
Repeat Steps 1-9 with other cuff and sleeve opening. 
And there you are! Snazzy thumbhole cuffs to keep your hands warm and toasty!
Give this a try on the Alpine Sweatshirt, Cassia Cardigan, or Hawthorn Henley!
Happy Making!
Rachelle