Stitch
Zigzag stitch
A stitch that swings the needle side to side as the fabric feeds. Use it whenever you need stretch — or to finish a raw edge so it won't fray.
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What it is
Between each puncture, the needle shifts laterally — left, then right, then left again. The result is a series of diagonal stitches forming a zigzag pattern. Because the thread crosses diagonally, the seam can stretch a little before the thread is taut, which is what makes it useful on stretchy fabric.
Two main uses
Finishing raw edges
Most fabrics fray at the cut edge. A zigzag along the edge wraps thread around it and stops the fraying. Set the stitch to about 3.0 mm length, 4.0 mm width and sew so the right swing of the zigzag goes just off the edge of the fabric.
(A serger does this faster and cleaner, but a zigzag on your sewing machine is the no-extra-equipment option and works fine for most things.)
Sewing stretchy fabric
For knits, jersey, swimwear, or anything with stretch: a straight stitch will pop when the fabric stretches. A narrow zigzag (around 1.0 mm width, 2.5 mm length) lets the seam stretch with the fabric.
Width and length
Two dials matter here:
| Setting | What it controls |
|---|---|
| Stitch width | How far the needle swings left to right (in mm) |
| Stitch length | How far the fabric feeds between each puncture |
A short length + wide width = a dense, almost-solid line of zigzag (used for buttonholes and bartacks). A long length + narrow width = a barely-zigzag line that mostly behaves like a straight stitch but with a tiny bit of give.
A note on tension
Zigzag tension is often slightly looser than straight-stitch tension. If your zigzag puckers the fabric, try lowering top tension by half a number.