The basic process: attach interfacing, sew the collar, turn it, and stitch it to the neckline

Sewing a collar means joining two fabric pieces together, turning them right-side out, and then stitching that finished collar to the neckline of your garment. The collar itself is sewn first — you stitch the two layers together on three sides, leave the bottom open, turn it inside out through that opening, and press it flat. Then you pin the collar to the neckline (usually with the seam allowance tucked inside) and stitch it down. The whole process takes about 30 to 45 minutes once you have your pattern pieces cut and your interfacing applied.

The key to a collar that lies flat and looks professional is interfacing — a stabilizing fabric you fuse to the underside of one collar piece before you sew anything. This keeps the collar from rolling or puckering and gives it shape. Without it, your collar will look limp and won't hold its form.

Key Takeaways

  • Fuse interfacing to the underside of one collar piece before you sew, using a pressing cloth to protect your iron and fabric.
  • Sew the two collar pieces together on three sides with a 5/8-inch seam allowance, leaving the bottom (neckline edge) open.
  • Trim the seam allowance to 1/4 inch, clip the corners diagonally, and turn the collar right-side out through the opening.
  • Press the collar flat, then pin it to the neckline with the seam allowance folded inside, and stitch it down with a 5/8-inch seam allowance.
  • Topstitching around the outer edge of the collar (1/8 inch from the fold) is optional but gives a more finished look and helps the collar stay in place.

Prepare your collar pieces and explore interfacing

Cut two collar pieces from your pattern. One piece will be the top collar (the side people see) and one will be the undercollar (the side against your neck). Lay the undercollar piece on your ironing board with the wrong side facing up. Place the interfacing on top of it, also wrong side up, so the adhesive side touches the fabric.

Set your iron to the heat recommended on the interfacing package — usually medium to medium-high. Lay a pressing cloth (a thin cotton scrap or a commercial pressing cloth) over the interfacing to protect your iron. Press down firmly for 10 to 15 seconds, then lift and move to the next section. Work across the entire piece until the interfacing is fused. Let it cool for a minute before you pick it up.

Sew the collar pieces together

Place the two collar pieces with right sides facing each other (the pretty sides touching). Pin around three sides: the two short ends and the outer curved edge. Leave the bottom edge (the neckline edge) unpinned and open — this is where you will turn the collar right-side out later.

Sew around the three pinned sides using a 5/8-inch seam allowance. Start at one end of the neckline edge and sew to the corner, then around the outer edge, and down to the other end of the neckline edge. Backstitch at the beginning and end. Remove the pins as you go.

Trim, clip, and turn the collar

Trim the seam allowance down to 1/4 inch all the way around the three sewn sides. This reduces bulk so the collar will turn smoothly and lie flat. At each corner (where the short ends meet the outer edge), clip diagonally across the corner, cutting close to the stitching without cutting through it. These diagonal clips let the corner turn sharp and crisp instead of bunching.

Reach through the open neckline edge and grab the collar from the inside. Pull gently and steadily to turn the collar right-side out. Use a point turner or the blunt end of a chopstick to push the corners out fully from the inside. Press the collar flat on your ironing board, using the point turner to make sure the seams lie exactly on the edge and the corners are sharp.

Attach the collar to the neckline

Fold the seam allowance of the open neckline edge to the inside of the collar (the side that will face your neck) and press it. This creates a finished edge. Now pin the collar to the neckline of your garment, matching the center marks and the shoulder seams. The seam allowance should be tucked inside the collar, hidden from view.

Sew the collar to the neckline using a 5/8-inch seam allowance. Sew slowly around the curve — the neckline is curved and the collar is curved, so you may need to ease them together slightly. Backstitch at the beginning and end. Remove the pins as you go.

Finish with topstitching (optional but recommended)

Topstitching — a visible line of stitching on the outside of the garment — is not required but makes the collar look more polished and helps it stay in place. Sew 1/8 inch from the outer edge of the collar all the way around, using a thread color that matches your fabric or contrasts intentionally if you want a decorative look.

Topstitching also secures the seam allowance inside the collar and prevents it from rolling out. If you choose to do it, use a walking foot on your machine if you have one — it helps feed the layers evenly and prevents puckering.

Common mistakes and how to avoid them

Forgetting interfacing is the most common mistake. Without it, the collar will look soft and droopy and won't hold its shape. Always fuse interfacing to the undercollar piece before you sew anything.

Sewing the collar to the neckline with the seam allowance sticking out (not folded inside) creates a bulky, unfinished look. Always fold that seam allowance to the inside before you pin and sew.

Not clipping the corners before turning creates thick, bunched corners that won't look crisp. Take the time to clip diagonally at each corner, and use a point turner to push the corners out fully after turning.

Sewing too close to the edge when you attach the collar to the neckline can cause the seam allowance to show or the collar to roll. Stick to a consistent 5/8-inch seam allowance and sew slowly around curves.

Frequently Asked Questions

What if my collar pieces are not perfectly symmetrical?

Small differences are normal and won't show once the collar is sewn. If one piece is noticeably larger, trim both pieces to match before you fuse the interfacing. Lay them on top of each other, line up the neckline edges, and trim the outer edges to match.

Can I use a regular presser foot or do I need a special one?

A regular presser foot works fine for sewing a collar. A walking foot helps if your fabric is slippery or stretchy, but it is not required. The most important thing is to sew slowly and keep your seam allowance even.

What thread should I use?

Use thread that matches your fabric color for the main seams so the stitching blends in. For topstitching, you can use matching thread or a contrasting color if you want the stitching to show. Use all-purpose polyester thread or cotton thread rated for your fabric weight.

Do I have to topstitch or can I skip it?

Topstitching is optional. If you skip it, the collar will still be attached and functional, but it may not look as finished and the seam allowance inside may roll out over time. Topstitching takes an extra 10 minutes and makes a visible difference in appearance.

What if my neckline is very curved or my collar is very wide?

Ease the pieces together slowly and use plenty of pins to hold them in place before you sew. Sew slowly and stop frequently to adjust the fabric. If the curve is very tight, you may need to clip into the seam allowance of the garment neckline (not the collar) to help it curve smoothly.