Finishing a seam means securing the raw fabric edges so they don't fray or come apart in the wash
When you sew two pieces of fabric together, you create a line of stitches. The edges of the fabric on either side of that seam are raw—they're cut, exposed, and will gradually unravel if you leave them alone. Finishing a seam means treating those raw edges so they stay intact through washing, wearing, and time. The method you choose depends on your fabric type, the garment's purpose, and what tools you have on hand.
Most seams in everyday clothing are finished with one of three basic techniques: a zigzag stitch, a serger (also called an overlock machine), or a binding. Each one works differently and produces a different look, but all three do the same job—they seal the edge so it won't fray.
Key Takeaways
- A zigzag stitch run along each raw edge is the simplest finish and works on most home sewing machines without extra equipment.
- A serger cuts and finishes both edges in one pass, which is faster but requires a separate machine that costs more than a standard sewing machine.
- Binding—folding fabric strip over the edge and stitching it down—creates a neat, durable finish and works well on knits and stretchy fabrics.
- The best finish for your seam depends on whether your fabric is woven or knit, how much the garment will be washed, and whether the seam will be visible.
The zigzag stitch: the standard home sewing finish
A zigzag stitch is the most common way to finish a seam on a regular sewing machine. After you've sewn your seam with a straight stitch, you trim the seam allowance to about 1/4 inch (or whatever your pattern calls for), then run a zigzag stitch along each raw edge separately. The zigzag catches the fabric fibers and locks them in place so they can't unravel.
To do this: set your machine to a zigzag stitch (usually marked with a zigzag symbol on the stitch dial), adjust the width to about 2 to 3 millimeters, and the length to 2 to 2.5 millimeters. Place one raw edge under the presser foot so the needle goes just off the edge of the fabric on the left swing and catches the fabric on the right swing. Sew slowly and steadily. Repeat on the other raw edge. This works on woven fabrics and lighter knits, though knits may still curl slightly at the edge.
Using a serger for a professional finish
A serger (or overlock machine) is a specialized sewing machine that cuts and finishes a seam edge in one step. It uses multiple threads—usually three or four—to wrap around the edge of the fabric, creating a neat, professional-looking finish that won't fray. Many garment factories use sergers because they're fast and produce a consistent result.
If you own a serger, you don't need to trim the seam allowance first. You straightforward guide the raw edge under the presser foot, and the machine cuts away the excess fabric and finishes the edge at the same time. A serger is more expensive than a standard sewing machine (typically $300 to $1000 or more), so most home sewers don't own one. If you have access to one at a community makerspace or a friend's house, it's worth learning, but it's not necessary for basic sewing.
Binding: a durable finish for knits and visible seams
Binding means wrapping a strip of fabric around the raw edge and stitching it down. This creates a strong, neat finish that looks intentional and works especially well on knits, stretchy fabrics, and seams that will be visible (like the armhole of a sleeveless shirt). Binding also prevents the curling that can happen on knit edges.
To bind a seam: cut a strip of fabric (usually bias tape, which stretches slightly) about 1 inch wide. Fold it in half lengthwise, wrong sides together, and press it flat. Open it up, then place the raw seam edge into the fold and pin it in place. Stitch along the crease line, catching all layers. Fold the binding to the back side and stitch it down by hand or machine. This takes longer than a zigzag stitch but produces a finish that's both functional and visible, so it needs to look intentional.
French seams: finishing by enclosing the raw edges
A French seam is a method where you sew the seam twice, enclosing the raw edges inside. This is an older technique that creates a very neat, durable finish with no raw edges visible at all. It works best on lightweight woven fabrics and garments that will be washed frequently, like sheets or lightweight shirts.
To sew a French seam: sew your first seam with the fabric pieces right sides together, but use a narrower seam allowance than usual (about 1/4 inch). Trim the seam allowance close to the stitching. Then fold the fabric so the wrong sides are now together, press the fold, and sew again about 1/2 inch from the fold. This second seam encloses the raw edges from the first seam inside the fold. The result is a seam with no visible raw edges, but it does take twice as long to sew.
Choosing the right finish for your fabric and project
Woven fabrics fray more readily than knits, so they benefit from a finish. A straightforward zigzag stitch is usually enough for everyday cotton or linen garments. Knits curl at the edges, so a zigzag alone may not be enough—binding or a serger finish works better. Lightweight fabrics like voile or lawn can be finished with a narrow zigzag or a French seam. Heavy fabrics like denim or canvas don't fray as much, so a straightforward zigzag is fine.
Consider also whether the seam will be visible. If it's an inside seam (like a side seam on a shirt), a zigzag is usually sufficient. If it's a seam that shows (like a decorative seam on the outside of a garment), you might choose binding or a French seam so it looks intentional. Think about how often the garment will be washed—frequently washed items benefit from a stronger finish like binding or a French seam.
Common mistakes when finishing seams
The most common mistake is not finishing seams at all, which leads to fraying and a garment that falls apart after a few washes. Another mistake is finishing too close to the stitching line—if your zigzag is too narrow, it won't catch enough fabric to hold the edge. Make sure the needle swings off the edge on one side and catches fabric on the other.
On knits, using only a zigzag without binding can leave the seam curling and looking unfinished. If you're working with a knit, plan to bind the seam or use a serger. Finally, don't trim the seam allowance too short before finishing—leave at least 1/4 inch so you have something to work with. If you trim too close, the finish won't have enough fabric to grip.
Frequently Asked Questions
Do I have to finish every seam?
No. Seams inside a garment that won't be seen and won't be washed frequently can be left unfinished. However, seams that will be washed often, seams on knit fabrics, and any seam on a lightweight woven fabric should be finished to prevent fraying and extend the garment's life.
Can I use pinking shears instead of a zigzag stitch?
Pinking shears (scissors with a zigzag blade) cut a zigzag edge that slows fraying slightly, but they don't hold the fibers in place the way a stitch does. They work as a temporary measure on heavy fabrics, but a sewn finish is more durable and will last through many more washes.
What if my fabric is very stretchy or slippery?
Stretchy and slippery fabrics like lycra, satin, or rayon can be tricky. A binding finish works well because it holds the edge firmly. A serger is also good because it wraps thread around the edge. A regular zigzag may not hold as well, so test on a scrap first.
How do I finish a curved seam?
Curved seams (like armholes) can be finished the same way as straight seams, but you'll need to go slowly and guide the fabric carefully so the finish follows the curve. Binding works especially well on curves because it's flexible. A serger also handles curves well because it's designed to follow the edge automatically.
Can I finish a seam after the garment is already sewn together?
Yes. You can finish seams at any point, even after the garment is complete. straightforward guide each raw edge under your presser foot and explore your chosen finish. This is actually a common practice—many sewers finish seams after trying on the garment to make sure the fit is right.