Long sleeve tee shirts combine the comfort and convenience of a regular tee shirt with the extra warmth (or sun protection) of sleeves. You can buy a long sleeve tee shirt pattern, or cut apart an old tee shirt along the seams. If you use an old tee shirt, be sure to add at least 1/4 inch of extra fabric to each edge for seam allowance, and 1 extra inch along the lower edges of the tee shirt front, back and sleeves for hems. To make a long sleeve tee shirt from a short sleeve pattern, just extend the sleeve patterns so they’re long enough to cover your arms. You can finish the ends of the long sleeves with simple hems, or with cuffs made from ribbing.
Make a Long Sleeve Tee Shirt
Pick out a tee shirt pattern with long sleeves. Many tee shirt patterns come with several options for lengths and collar styles. Cut out the patterns, using the cutting lines for the size and style you need.
Pin the pattern pieces to the knit fabric. Depending on the pattern, you may need to fold the fabric in half right sides together and place some pieces on the fold. Cut out the pattern pieces.
Pin the front and back of the tee shirt right sides together. Sew the front and back of the tee shirt together along the shoulders and the sides below the armholes.
Pin the underarm edges of one tee shirt sleeve right sides together, then stitch the underarm seam. Turn the sleeve right side out.
Put the sleeve inside one armhole of the tee shirt. Pin the upper edges of the sleeve to the armhole, with the fabrics right sides together. Stitch the sleeve to the armhole.
Repeat steps 4 and 5 for the other sleeve, then turn the tee shirt right side out.
Hem the bottom of the tee shirt by folding the lower edge over 1/2 inch toward the inside of the shirt and pressing the fold flat. Fold the edge over another 1/2 inch and press it flat again. Topstitch the fold in place using matching thread.
Trim the ribbing if needed to make it 1/2 inch wider and longer than you want the finished collar. Sew the short ends of the ribbing together.
Pin the unfinished edge of the ribbing to the top of the tee shirt neck opening. Stitch the ribbing to the tee shirt using 1/2 inch seam allowance, then turn the ribbing right side up and press the seam flat. Topstitch along the seam to hold the ribbing in place if needed.
Finish the ends of the sleeves by hemming them (the same way you hemmed the lower edge) or by adding cuffs made from ribbing (the same way you added the collar). If you choose cuffs, you may need to shorten the ends of the sleeves first so that the cuffs will make the sleeves the right length.