Sewing a turtleneck collar starts with measuring your neckline, cutting a ribbed fabric tube, and attaching it with a serger or stretch stitch

A turtleneck collar is a continuous tube of ribbed fabric that sits high on the neck. To sew one, you measure your neckline opening, cut a rectangle of ribbed knit fabric to those dimensions, fold it in half lengthwise, and sew the short ends together to form a tube. Then you attach that tube to your neckline using a serger (if you have one) or a sewing machine set to a stretch stitch, which keeps the seam from snapping when the fabric moves.

The whole process takes about an hour once you have your materials. You do not need advanced sewing skills, but you do need to work with ribbed fabric—the kind that stretches and recovers—and use a stitch that moves with it. A regular straight stitch will break the thread when you pull the finished garment over your head.

Key Takeaways

  • Measure your neckline opening (the actual hole, not the shoulder seam) to determine how wide your ribbed fabric rectangle should be.
  • Ribbed knit fabric is essential because it stretches to fit over your head and recovers to hug your neck; woven fabric will not work.
  • A serger with a differential feed setting handles stretchy seams best, but a regular sewing machine with a ballpoint needle and stretch stitch produces good results too.
  • Fold your ribbed rectangle in half lengthwise before attaching it to the neckline so the finished collar has a folded edge at the top.

Measure your neckline opening accurately

The neckline opening is the actual hole you will pull the collar through—not the shoulder seam line. Lay your sweater or top flat on a table and measure straight across the opening from one shoulder seam to the other, then add about half an inch for seam allowance. Write this number down; it is the width of your ribbed fabric rectangle.

For the height of the rectangle, decide how tall you want your finished turtleneck to be. Most turtlenecks sit 2 to 3 inches high on the neck. Since you will fold the fabric in half lengthwise, cut your rectangle twice that height—so for a 2.5-inch finished collar, cut a rectangle 5 inches tall. Add half an inch for seam allowance on both the top and bottom, so you would cut a 6-inch-tall rectangle.

Choose and prepare ribbed knit fabric

Ribbed knit fabric is the only fabric that works for a turtleneck collar. It has vertical ridges that run the length of the fabric, and it stretches horizontally (across the ridges) while staying stable lengthwise. This is the opposite of how you need it to behave: you want the stretch to go around your neck, not up and down. So when you cut your rectangle, the ridges should run parallel to the short ends of the rectangle, not the long ends.

If you are buying fabric new, look for ribbing sold by the yard at a fabric store—it comes in rolls and is already the right width (usually 60 inches). If you are reusing ribbing from an old sweater, cut a rectangle from the ribbed cuff or hem. Ribbing is forgiving; slight imperfections in your rectangle will not show in the finished collar.

Sew the short ends of the rectangle together

Fold your ribbed rectangle in half lengthwise so the two long edges meet. The fabric should now look like a long, narrow strip. Place it on your sewing machine with the fold on your left and the two raw edges on your right, facing you.

Sew the two short ends together using a stretch stitch (also called a ballpoint stitch or elastic stitch on most machines). Set your stitch length to 2.5 to 3 mm and use a ballpoint needle, which slides between the fibers of knit fabric instead of piercing them. Sew about half an inch from the raw edges. When you finish, you will have a tube of ribbed fabric with one folded edge (the top of your finished collar) and one seam (which will be hidden inside the neckline).

Attach the collar to your neckline

Pin the seamed edge of your ribbed tube to the neckline opening of your sweater, with the right side of the ribbing facing the right side of the sweater body. The folded edge of the tube should point upward, away from the sweater. Distribute the pins evenly around the neckline so the ribbing does not bunch.

If you have a serger, use it with a 4-thread overlock stitch and differential feed set to 1.0 or slightly higher. This stitch will stretch as it sews and finish the raw edges at the same time. If you are using a regular sewing machine, use a stretch stitch or a narrow zigzag stitch, again with a ballpoint needle. Sew slowly and let the fabric feed naturally—do not pull it. The stretch stitch will compress slightly as you sew, which is normal and correct.

When you reach the end, overlap your stitching by about half an inch and tie off the thread. Trim any loose threads and try on your finished turtleneck.

Troubleshoot common problems

If your collar is too loose and falls down, your neckline opening was measured too wide, or your ribbed rectangle was cut too tall. Turtlenecks should sit snugly; if you can fit two fingers under it, it is too loose. You can unpick the seam, cut a narrower rectangle, and resew it.

If your collar is too tight and cuts off circulation, your neckline was too narrow or your rectangle too short. This is harder to fix without starting over, so measure carefully the first time. A good test: you should be able to fit one finger comfortably under the finished collar.

If the seam is puckering or the thread is breaking, you are likely using a regular straight stitch or a needle designed for woven fabric. Switch to a ballpoint needle and a stretch stitch, and sew more slowly. Knit fabric needs a stitch that moves with it.

Alternatives if you do not have a serger

A serger makes the job faster and the seam more professional, but it is not required. A regular sewing machine with a stretch stitch and ballpoint needle produces a collar that works just as well and lasts just as long. The only difference is that your seam will not be finished (the raw edges will be inside the collar), but since they are hidden, this does not affect how the garment looks or wears.

If your machine does not have a stretch stitch, a narrow zigzag stitch (width 1.5 to 2 mm, length 2 to 2.5 mm) will also work. Test it on a scrap of ribbed fabric first to make sure the stitch length and width feel right before you sew your actual collar.

Frequently Asked Questions

Can I use regular knit fabric instead of ribbed knit?

Regular knit fabric will stretch too much and will not hold its shape around your neck. Ribbed knit has a structure that makes it recover after stretching, so it hugs your neck without sagging. If you cannot find ribbing, a turtleneck collar will not work well with other fabrics.

What if my neckline is too small to fit the ribbed tube over my head?

Your ribbed rectangle was cut too narrow. Unpick the seam connecting the short ends, cut a wider rectangle, and resew it. The collar should stretch enough that you can pull it over your head with a little effort, but not so much that it falls down when you wear it.

Do I need a serger to sew a turtleneck collar?

No. A regular sewing machine with a stretch stitch and ballpoint needle works well. A serger finishes the seam edges and looks more professional, but the collar will function and last just as long without one.

How do I know if my stitch is stretchy enough?

Sew a test seam on a scrap of ribbed fabric, then pull it hard. If the thread breaks, your stitch is not stretchy enough. If it stretches without breaking and returns to normal when you release it, you have the right stitch. Adjust your stitch type or length and test again.

Can I add a turtleneck collar to a sweater that already has a crew neck?

Yes, but you will need to remove the existing neckline binding first. Carefully unpick the stitches holding the old binding in place, trim any loose threads, and measure the new neckline opening. Then follow the steps above to attach your ribbed turtleneck collar.