Sewing a collar on a shirt requires pinning the collar to the neckline, stitching it in place, and then folding and topstitching the seam allowance flat
A collar is sewn in two stages: first you attach the collar pieces to the shirt body, then you fold the seam allowance to the inside and stitch it down so the raw edges are hidden. The whole process takes about 30 to 45 minutes once you have your pieces cut and ready. You will need a sewing machine, thread that matches your fabric, pins, scissors, and an iron.
The key is to sew slowly at the curves of the neckline, backstitch at the start and end of each seam, and press with an iron between steps so your collar lies flat and even. If your stitches wander or your collar sits crooked, you can pick out the thread with a seam ripper and try again—fabric is forgiving, and most mistakes are invisible once you press them.
Key Takeaways
- Pin the collar to the neckline with right sides facing, then sew a straight seam 5/8 inch from the edge, backstitching at the start and end.
- Trim the seam allowance to 1/4 inch, clip into the curves at the neckline so the collar will turn smoothly, and press the seam open with an iron.
- Fold the collar seam allowance to the inside of the shirt, pin it down, and topstitch 1/8 inch from the fold to hold it flat and hide the raw edges.
- Press the finished collar with an iron on medium heat to set the shape and remove any puckers or wrinkles from sewing.
Prepare your collar pieces and neckline
Before you pin anything, make sure your collar pieces are cut and interfaced. Interfacing is a layer of stiff fabric fused to the underside of the collar to give it shape and keep it from drooping. If your pattern calls for interfacing, fuse it to the wrong side of one collar piece following the package directions—usually you lay the interfacing shiny side down on the fabric and press it with a hot iron for 10 to 15 seconds.
Cut two collar pieces from your fabric. Sew them together along the outer edges (the long sides and the point or curve), leaving the neckline edge open. Trim the seam allowance to 1/4 inch, clip the corners or curves so they will turn smooth, and turn the collar right side out. Press it flat with an iron. Now you have one finished collar piece ready to attach to the shirt.
Check that your shirt neckline is also ready: the shoulder seams should be sewn and pressed, and the neckline edge should be cut cleanly. If you are working from a pattern, the neckline is usually already marked with notches or dots to show where the collar should sit.
Pin and sew the collar to the neckline
Lay your shirt flat with the right side facing up. Place the collar on top with the right side of the collar facing down (so the finished side is against the shirt). Line up the neckline edge of the collar with the neckline edge of the shirt. Use the notches on your pattern pieces to match them up—usually the center back of the collar lines up with the center back of the shirt, and the collar points line up with the front edges.
Pin the collar in place every 2 to 3 inches, working from the center out toward the edges. The neckline curves, so ease the collar around the curve gently as you pin—do not stretch it. Once the collar is pinned all the way around, check that it sits evenly and that the ends line up with the front edges of the shirt.
Sew the collar to the neckline using a straight stitch, 5/8 inch from the edge. Sew slowly, especially at the curves, and backstitch at the start and end. Remove the pins as you go. When you reach a curve, stop with the needle down, lift the presser foot, and pivot the fabric slightly to follow the curve—this keeps your seam line smooth and even.
Trim and clip the seam allowance
Once the collar is sewn on, trim the seam allowance down to 1/4 inch. Use sharp scissors and cut close to your stitching line, but do not cut into the stitches themselves. This reduces bulk so the collar will not be lumpy when you fold it over.
Next, clip into the seam allowance at the curves of the neckline. Make small cuts perpendicular to the seam line, about 1/8 inch apart, stopping just short of your stitching. These clips allow the seam allowance to spread out and lie flat when you turn the collar to the inside—without them, the fabric will bunch and pucker.
Press the seam open with an iron on medium heat. Lay the shirt flat, open the seam allowance with your fingers, and press it flat on both sides. This sets the seam and makes the next step easier.
Fold the seam allowance to the inside and pin it
Turn the shirt inside out or fold it so you can see the wrong side of the neckline. Fold the seam allowance of the collar to the inside of the shirt, tucking the raw edge under so it is hidden. The fold should sit right at the stitching line you just made. Pin it in place every 2 to 3 inches, making sure the fold is even all the way around.
At the front edges of the shirt, the collar seam allowance will meet the front facing or placket. Fold these corners neatly so they lie flat and do not stick out. If your pattern has a front facing, the facing will cover this seam allowance, so you do not need to fold it under—just let it sit naturally.
Topstitch the collar seam allowance flat
With the collar seam allowance pinned to the inside, sew a line of stitching 1/8 inch from the fold. This is called topstitching, and it holds the seam allowance flat and out of sight. Use a straight stitch and sew slowly so your line is even and parallel to the fold.
Sew all the way around the neckline, removing pins as you go. Backstitch at the start and end. The topstitching line will be visible on the inside of the shirt, but it will be hidden under the collar when the shirt is worn.
If you want a more finished look, you can topstitch from the outside of the shirt instead, 1/8 inch from the neckline seam. This creates a visible line of stitching on the right side of the collar and is common on casual shirts and polo shirts. Either method works—it is a matter of style.
Press the finished collar
Press the entire collar with an iron on medium heat. Lay the shirt flat, smooth the collar into place, and press from the inside first, then from the outside. This sets the shape of the collar and removes any wrinkles or puckers from sewing.
Pay special attention to the neckline seam and the edges of the collar. Press along the fold line so it is crisp and even. If the collar has a point, press the point sharply so it is defined.
Once the collar is pressed, it should lie flat against the shirt and feel smooth. If you see any puckers or if the collar is not sitting evenly, you can dampen it slightly with a spray bottle and press it again.
Frequently Asked Questions
What if my collar is crooked or does not sit evenly?
Pick out the topstitching with a seam ripper, unpin the seam allowance, and repin it so it sits evenly. Then topstitch again. If the collar itself is crooked, you may need to pick out the main seam that attaches the collar to the neckline and resew it, but this is rare if you pinned carefully the first time.
Can I sew a collar on by hand instead of with a machine?
Yes. Use a backstitch for the main seam that attaches the collar to the neckline, and a slip stitch for the topstitching on the inside. Hand sewing takes longer but gives you more control, especially on curves. Make your stitches small and even, about 1/8 inch long.
What if I do not have interfacing?
The collar will be softer and may droop slightly, but you can still sew it on. Interfacing is optional—it just gives the collar more structure. If you want to add it later, you can fuse it to the finished collar from the inside, though this is trickier than fusing it before you sew.
How do I sew a collar on a knit shirt?
Use a ballpoint needle and a stretch stitch or a narrow zigzag instead of a straight stitch. This allows the seam to stretch with the fabric so it does not break when you wear the shirt. Knit fabric is more forgiving than woven fabric, so do not worry if your seam is not perfectly straight.
Should I topstitch from the inside or the outside?
Both work. Topstitching from the inside is hidden and gives a clean look. Topstitching from the outside is visible and is common on casual or sporty shirts. Choose based on the style you want and what your pattern recommends.