The two ways to attach elastic: direct and casing

You can sew elastic in two main ways. Direct attachment means sewing the elastic straight onto the fabric edge—you stretch it as you sew, and it gathers the fabric. Casing means creating a tunnel in the fabric and threading the elastic through afterward. Direct attachment is faster for waistbands and cuffs. Casing works better when you want the elastic hidden and the fabric to look smooth on the outside.

Which method you choose depends on what you're making and how much the elastic needs to stretch. A fitted waistband on pajamas usually calls for direct attachment. A drawstring waist on linen pants often uses a casing so the elastic can move freely and the waistband stays flat.

Key Takeaways

  • Direct attachment means sewing elastic to the fabric edge while stretching it; casing means creating a tunnel and threading elastic through.
  • Measure your elastic to fit snugly around the body part—usually 1 to 2 inches smaller than the opening—before you sew.
  • Use a zigzag stitch or stretch stitch on your machine to keep the seam from breaking when the elastic moves.
  • Pin elastic in quarters to keep it from bunching, and stretch it evenly as you sew.
  • Test the fit before you finish the seam; you can adjust elastic length while the ends are still loose.

Measuring and preparing your elastic

Before you sew, measure how much elastic you need. Wrap the elastic around the body part it will fit—your waist, wrist, or leg—and pull it snug but not tight. It should feel like it will hold without cutting off circulation. Mark where the elastic meets itself, then remove it and measure that length. Write it down.

Most elastic for waistbands should be 1 to 2 inches smaller than the opening you're sewing it to. If your waistband opening is 30 inches around, cut elastic that is 28 to 29 inches long. Thinner elastic (like 1/2 inch wide) can be smaller; wider elastic (1 to 1.5 inches) usually needs less reduction because it distributes the stretch more evenly.

Cut your elastic cleanly with sharp scissors. If the cut edge is ragged, the elastic can fray and the threads can catch on your machine. Some people seal the cut ends with a lighter—hold the flame just close enough to melt the edge without burning it—but this is optional.

Direct attachment: sewing elastic to the fabric edge

Pin the elastic to the wrong side of your fabric in four equal sections. If your waistband is 30 inches around, mark at 0, 7.5, 15, and 22.5 inches. Do the same on the elastic. Pin at each mark so the elastic and fabric are aligned. The elastic should be on the inside of the garment, against the wrong side of the fabric.

Set your machine to a zigzag stitch or a stretch stitch if your machine has one. A straight stitch will snap when the elastic stretches. Use thread that matches your fabric. Set the stitch width to medium (about 2.5 to 3) and length to medium (about 2.5). Test on a scrap of fabric and elastic first.

Start sewing at one of your pins. Hold the fabric with one hand and gently stretch the elastic ahead of the presser foot with the other hand. Keep the stretch even—do not pull hard, just enough so the elastic lies flat against the fabric as you sew. The needle should go through both the elastic and the fabric. Sew slowly so you can control the stretch.

When you reach the next pin, release the stretch slightly and let the fabric bunch up naturally. This bunching is what makes the elastic work—it gathers the fabric so the waistband fits snugly. Continue around, stretching between pins and releasing at pins, until you reach the end.

Joining the elastic ends

When you have sewn almost all the way around, stop about 2 inches before you reach your starting point. Leave the needle in the fabric and lift the presser foot. Overlap the two ends of the elastic by about 1/2 inch and pin them together. Make sure the overlap is flat and the elastic is not twisted.

Lower the presser foot and sew over the overlap several times—forward and backward—to lock it in place. Then continue sewing the last 2 inches of the seam, stretching the elastic as you go. Backstitch at the end to find the thread.

Trim any loose threads. If you used a zigzag stitch, the seam should be flexible enough to move with the elastic. If the seam feels stiff, you may have used too tight a stitch or too heavy a thread.

Making a casing for elastic

A casing is a tunnel of fabric that the elastic slides through. To make one, fold the fabric edge inward twice—usually 1/2 inch the first time, then another 1/2 inch—so the raw edge is hidden inside. Press the fold flat with an iron. Pin it in place.

Sew close to the inner fold, leaving a 1 to 2 inch opening so you can thread the elastic through later. Use a straight stitch and sew slowly around the entire opening. Backstitch at the beginning and end. The opening should be in a seam or an inconspicuous place if possible.

Cut a safety pin to the elastic or tie a knot in one end. Thread the safety pin through the opening and push it through the casing, gathering the fabric as you go. The safety pin will pull the elastic along behind it. When the elastic comes out the other side, remove the safety pin.

Overlap the elastic ends by 1/2 inch and sew them together with a zigzag stitch, going back and forth several times. Then push the joined elastic back into the casing and sew the opening closed with a ladder stitch (an invisible stitch that runs along the fold) or a straightforward straight stitch.

Fixing common problems

If the elastic bunches unevenly, you probably did not pin it in quarters or did not stretch it evenly as you sewed. You can remove the stitches with a seam ripper, adjust the elastic, and sew again. It is easier to fix this before you join the ends.

If the seam breaks or pops when you wear the garment, you used a stitch that is too tight or too short. Zigzag and stretch stitches are designed to move with elastic; a straight stitch cannot. If you have already sewn it, you will need to remove the seam and sew it again with a zigzag.

If the elastic feels loose or slides down, it is too long. Measure the opening again and cut a new piece of elastic 1 to 2 inches smaller. Remove the old elastic and sew the new one on. Elastic stretches over time, so a waistband that fits perfectly today may feel loose in a year—this is normal.

Choosing the right elastic for your project

Not all elastic is the same. Braided elastic is flat and smooth and works well for waistbands and cuffs. Knit elastic is soft and stretches in all directions, making it comfortable for underwear and swimwear. Woven elastic is sturdy and holds its shape, good for heavy fabrics.

Elastic also comes in different widths. Narrow elastic (1/4 to 1/2 inch) works for cuffs and light fabrics. Medium elastic (3/4 to 1 inch) is standard for waistbands. Wide elastic (1.5 inches or more) distributes pressure over a larger area and is more comfortable for tight-fitting garments.

If you are sewing a stretchy fabric like jersey or spandex, use a softer elastic like knit elastic. If you are sewing a heavy fabric like denim or canvas, use a sturdier elastic like braided or woven. The elastic should be slightly narrower than the seam allowance so it does not stick out from the edge.

Frequently Asked Questions

Can I use a straight stitch to sew elastic?

You can, but the seam will break or pop when the elastic stretches. A zigzag or stretch stitch allows the thread to move with the elastic. If you have already sewn with a straight stitch, remove it and sew again with a zigzag.

How do I know if my elastic is too tight or too loose?

Put on the garment and check the fit. The elastic should feel snug but not uncomfortable—you should be able to fit one finger under it. If it slides down, it is too loose; if it leaves marks on your skin, it is too tight. You can adjust it before you finish sewing by removing the stitches and changing the elastic length.

What if I sew the elastic ends together but they come apart?

You did not overlap them enough or did not sew back and forth enough times. Remove the stitches, overlap the ends by at least 1/2 inch, and sew over the overlap at least four times—forward and backward—with a zigzag stitch. Make sure the overlap is flat and not twisted.

Can I reuse elastic from an old garment?

Yes, if it still stretches and feels firm. Old elastic loses elasticity over time, so test it by stretching it and releasing it—it should snap back quickly. If it feels loose or does not return to its original length, replace it with new elastic.

Do I need to pre-wash elastic before sewing?

Most modern elastic does not shrink, but if you are making a garment you plan to wash frequently, wash a small piece of the elastic in hot water and dry it to see if it shrinks. If it does, pre-wash the entire length before you sew. This prevents the elastic from shrinking after you have finished the garment.