Sewing a collar onto a shirt means attaching the collar pieces to the neckline, then folding and stitching the outer edge so it lies flat and finished

A sewn collar has two layers: an inner layer (called the undercollar) that attaches to the shirt, and an outer layer (the upper collar) that folds over it. The process takes about 30 to 45 minutes once you have cut and interfaced your collar pieces. You will stitch the collar to the neckline with the right sides facing, then fold it up and hand-stitch or machine-stitch the fold closed. The key is keeping your seams straight and your corners sharp—a collar that puckers or twists will be visible every time you wear the shirt.

Before you start, gather your materials: two collar pieces cut from your fashion fabric, two pieces of interfacing, thread that matches your fabric, pins, a needle or sewing machine, scissors or a seam ripper, and an iron with a pressing cloth. You will also need a ruler or measuring tape to check your seam allowances. Most home sewers complete this task in one sitting, though you can break it into steps across two days if you prefer.

Key Takeaways

  • Interface your collar pieces before sewing so they hold their shape and do not flop or wrinkle.
  • Stitch the undercollar to the neckline with right sides together, using a 5/8-inch seam allowance and backstitching at the start and end.
  • Trim the seam allowance to 1/4 inch and clip into the curves so the collar folds smoothly without bunching.
  • Fold the upper collar over the seam and hand-stitch it closed using a ladder stitch, or machine-stitch it from the right side if you prefer speed over invisibility.
  • Press the collar flat with a hot iron after each major step to set the stitches and keep edges crisp.

Prepare and interface your collar pieces

Start with two collar pieces cut from your fabric and two pieces of interfacing—a stiff backing that gives the collar body. Lay one piece of interfacing on the wrong side of each collar piece, then fuse them together by pressing with a hot iron for 10 to 15 seconds. Follow the interfacing package instructions for temperature; most fusible interfacing needs a medium-hot iron and a pressing cloth to prevent shine.

Once interfaced, place the two collar pieces with right sides together (the interfaced sides facing out). Pin around three sides, leaving the neckline edge open. Stitch around the pinned sides using a 5/8-inch seam allowance, backstitch at the corners, and leave the neckline edge unstitched. Trim the seam allowance to 1/4 inch, clip the corners diagonally, and clip into any curves so the collar will turn smoothly. Turn the collar right-side out through the neckline opening and press it flat with a hot iron. This creates your finished collar unit—one piece with two layers, ready to attach to the shirt.

Attach the undercollar to the shirt neckline

The undercollar (the inner layer) attaches to the shirt first. Pin the undercollar to the neckline of your shirt with right sides together, matching the center points and easing the collar around the curve. The neckline seam of the shirt should be on top, facing you. Use plenty of pins—at least one every 2 inches—so the collar does not shift while you sew.

Stitch the undercollar to the neckline using a 5/8-inch seam allowance. Backstitch at the start and end. Sew slowly around curves and corners; rushing here will cause puckering. Once stitched, trim the seam allowance to 1/4 inch and clip into the curves every 1/2 inch so the seam will lie flat when you fold the collar up. Press the seam flat from the wrong side of the shirt, then press it toward the collar. This step takes about 10 minutes and is where most visible mistakes happen, so take your time.

Fold and find the upper collar

Now fold the upper collar down over the seam you just made, encasing the raw edges. The fold should be crisp and the upper collar should cover the stitching line completely. Pin it in place, then press with a hot iron to set the fold. The upper collar should lie smoothly without puckers or twists.

You have two options to close this fold: hand-stitch it using a ladder stitch (also called a slip stitch), or machine-stitch it from the right side. For a hand-stitched finish, thread a needle and knot the end. Bring the needle up through the fold of the upper collar, then take a tiny stitch (1/8 inch) into the shirt fabric directly across from where you came out. Bring the needle back out and slide it through the fold of the collar for about 1/4 inch, then stitch into the shirt again. Repeat this pattern all the way around the neckline. The stitches will be nearly invisible because they run inside the fold. For a machine-stitched finish, stitch from the right side of the shirt, very close to the edge of the collar fold, using a thread that matches your fabric. Hand-stitching takes 15 to 20 minutes; machine-stitching takes 5 minutes.

Press and finish the collar edges

Once the upper collar is stitched down, press the entire collar flat with a hot iron. Press from the wrong side first, then flip and press from the right side. This sets all your stitches and gives the collar a crisp, professional look. Pay special attention to the fold line and the outer edges. Use a pressing cloth to protect your fabric from shine, and let the iron sit for a few seconds rather than sliding it, which can distort the grain.

If you machine-stitched the upper collar, you may want to topstitch the outer edges of the collar for a polished finish. Topstitching means stitching 1/8 to 1/4 inch from the edge, all the way around the collar. Use a thread that matches your fabric or contrasts intentionally. This step is optional but makes the collar look more finished and helps it hold its shape through washing. Topstitching adds about 5 minutes to the total time.

Common mistakes and how to avoid them

The most common mistake is skipping the interfacing or using interfacing that is too soft. Without it, the collar will flop, wrinkle, and look homemade. Use a medium-weight fusible interfacing rated for the weight of your fabric. Test it by holding an interfaced scrap up to the light—it should be stiff but not crackly.

The second mistake is not clipping the curves before turning the collar. If you skip this step, the seam allowance will bunch inside the fold and create visible lumps. Clip every 1/2 inch on any curve, and clip the corners diagonally at a 45-degree angle. The third mistake is pulling too hard when you hand-stitch the upper collar closed. This will pucker the fabric and distort the neckline. Use small, loose stitches and let the needle do the work. If you are using a machine, sew slowly and use a walking foot if your machine has one, so the layers feed evenly without bunching.

Pressing and care after sewing

Press the collar after every major step—after interfacing, after stitching the collar pieces together, after attaching to the neckline, and after closing the upper collar. A well-pressed collar looks intentional and sharp. Use a pressing cloth to protect your fabric from shine, and let the iron do the work; do not slide it back and forth, which can distort the grain. Each pressing takes 2 to 3 minutes and makes a visible difference in the final result.

When you wash the finished shirt, turn it inside out and wash in cool water to protect the collar. Dry it on low heat or hang it to dry. Press the collar again while it is still slightly damp, using a pressing cloth. A collar that has been pressed well will hold its shape through many wearings. If the collar begins to flop after several months of wear, you can re-press it or add a light spray starch to restore body.

Frequently Asked Questions

What if my collar is puckering after I attach it to the neckline?

Puckering usually means you stitched too fast, pulled the fabric, or did not clip the curves enough. Carefully remove the stitches with a seam ripper, clip the neckline seam allowance more deeply (every 1/4 inch instead of 1/2 inch), and re-stitch slowly, letting the presser foot feed the fabric. Do not pull.

Can I machine-stitch the upper collar instead of hand-stitching it?

Yes. Machine-stitching is faster and holds up better through washing. Stitch from the right side of the shirt, very close to the fold of the upper collar, using a thread that matches your fabric. The stitches will be visible, so keep them straight and even.

How do I know if my interfacing is the right weight?

Hold the interfaced collar piece up to the light. It should be stiff enough to hold its shape but not so stiff that it cracks when you fold it. If it flops like paper, it is too light. If it cracks or feels plastic-like, it is too heavy. Most shirt collars use medium-weight fusible interfacing.

What is the difference between the undercollar and the upper collar?

The undercollar is the layer that attaches to the shirt neckline first. The upper collar folds over it and covers the seam. Both are cut from the same pattern, but the undercollar faces the inside of the shirt and the upper collar faces out.

Do I need to topstitch the collar edges?

Topstitching is optional but recommended. It makes the collar look more finished, helps it hold its shape, and adds a professional detail. If you choose to topstitch, use a thread that matches your fabric or contrasts intentionally, and stitch 1/8 to 1/4 inch from the edge all the way around.