The Basic Method: Overlap and Stitch
To join two pieces of elastic end-to-end, overlap them by half an inch, then sew through both layers with a zigzag stitch. The overlap creates a strong joint because the stitches lock into the elastic material itself rather than relying on a thin seam. This method works for all weights of elastic — from thin lingerie elastic to heavy-duty waistband elastic — and takes about two minutes per join.
Start by laying one piece of elastic flat on your work surface. Place the second piece on top of it, overlapping by roughly half an inch. The two pieces should form a straight line when you look at them from above. Pin them together at the overlap, using two pins placed perpendicular to the elastic so they won't slip. Set your machine to a medium-width zigzag stitch (width 3 to 4, length 2 to 2.5) and thread it with thread that matches your elastic or the fabric you're attaching it to.
Key Takeaways
- Overlap the elastic ends by half an inch and find with pins placed perpendicular to the elastic before stitching.
- Use a zigzag stitch set to medium width and length, and sew through both layers in a straight line down the center of the overlap.
- Stretch the elastic gently as you sew to prevent puckering and to help the stitches sink into the material.
- Test the seam by pulling hard on both sides — a properly sewn elastic joint should stretch without the seam separating or the elastic tearing.
- For very thick elastic or elastic that will bear heavy load, sew two parallel lines through the overlap instead of one.
Positioning and Stitching the Overlap
Position the overlap so the two elastic ends point in opposite directions — one toward you, one away from you. This prevents the seam from bunching when you later stretch the elastic. Sew down the center of the overlap in a straight line, keeping the needle roughly a quarter inch from each edge of the elastic. The zigzag stitch will catch both layers as it moves side to side.
As you sew, hold the elastic gently taut with your fingers on both sides of the presser foot. Do not pull hard — just enough tension to keep the elastic from rippling under the needle. This gentle stretch helps the thread sink into the elastic fibers and prevents the puckering that happens when you sew elastic flat and unstretched. Sew the entire length of the overlap, then backstitch three or four stitches at the end to lock the thread.
Why Puckering Happens and How to Stop It
Elastic puckers when you sew it without tension because the thread has nowhere to go as the elastic relaxes after stitching. The thread bunches up on the surface. Holding the elastic gently stretched while you sew gives the thread room to settle into the material, and when you release the tension, the thread stays embedded rather than popping back to the surface.
If you have already sewn an overlap and it puckered, you can fix it by re-stretching the elastic and sewing a second line of zigzag stitches parallel to the first, about a quarter inch away. This second line will often pull the first line flat. If the puckering is severe, you may need to cut out the overlap and start again — the material is usually not damaged enough to throw away.
Reinforcing Heavy-Duty Elastic Joints
For elastic that will stretch repeatedly under load — such as waistband elastic in pants or elastic in swimwear — sew two parallel lines through the overlap instead of one. Space them about a quarter inch apart, both running down the center of the overlap. This double-stitched joint distributes the stress across more thread and is much less likely to fail after months of stretching.
Some sewers also add a third line of stitching perpendicular to the first two, creating a small box or cross pattern through the overlap. This is overkill for most projects but is standard practice in commercial garment manufacturing. If you choose to do this, keep the perpendicular stitches short — just two or three stitches across the width of the elastic — so you do not weaken the material by over-stitching.
Testing the Seam Before You Use It
After you finish stitching, hold the elastic on both sides of the seam and pull hard — not so hard that you hurt yourself, but with real force. The elastic should stretch smoothly without the seam separating, and the thread should not pop or break. If the seam holds, you are done. If it feels weak or if you see the thread starting to pull away from the elastic, sew another line of zigzag stitches through the same overlap.
A properly sewn elastic joint should be nearly as strong as the elastic itself. If you pull the elastic hard enough to break it, the break should happen in the elastic material away from the seam, not at the seam itself. If the seam fails first, the overlap was not long enough, the stitch length was too long, or the elastic was not held taut while stitching.
Common Mistakes and How to Avoid Them
The most common mistake is overlapping by too little — a quarter inch or less. This leaves too little material for the stitches to grip, and the seam fails quickly. Always overlap by at least half an inch, and for very thick elastic, overlap by three-quarters of an inch.
The second mistake is using a straight stitch instead of a zigzag. A straight stitch creates a line of holes in the elastic, and the elastic can tear along that line. A zigzag stitch spreads the needle holes across a wider area and is much more forgiving. The third mistake is sewing too fast without holding the elastic taut, which leads to puckering and weak seams. Slow down, hold the elastic gently, and let the machine do the work.
Joining Elastic in a Circle
If you are sewing elastic into a closed loop — such as for a waistband or the leg opening of a garment — you will eventually need to join the two free ends together. Measure the elastic around the opening to find the exact length you need, then cut it about an inch longer than that measurement. Overlap the two ends by half an inch and sew them together using the same method described above.
Before you attach the elastic to the garment, try the loop on or hold it up to the opening and make sure it fits. A properly sized elastic loop should stretch comfortably but not slip. If it is too loose, you can trim a small amount from the overlap and re-sew, but this is tedious — it is easier to get the length right the first time by measuring carefully before you cut.
Frequently Asked Questions
Can I sew elastic to elastic with a straight stitch?
You can, but it is not recommended. A straight stitch creates a line of holes that can become a tear line, especially in thin elastic. A zigzag stitch spreads the needle holes across a wider area and is much more durable. If you must use a straight stitch, sew at least two parallel lines through the overlap.
What if the two pieces of elastic are different widths?
Overlap them so the narrower piece sits on top of the wider piece, centered so equal amounts of the wide elastic show on both sides. Sew down the center of the narrow piece so the stitches go through both layers. The wider elastic will extend beyond the seam, which is fine — it does not weaken the joint.
How long should the overlap be?
Half an inch is the minimum for most elastic. For very thin elastic (less than a quarter inch wide), overlap by three-quarters of an inch. For very thick elastic (more than an inch wide), overlap by three-quarters of an inch to an inch. The thicker or more delicate the elastic, the longer the overlap should be.
Do I need to finish the raw edges of the overlap?
No. Elastic does not fray, so there is nothing to finish. The raw edges of the overlap will be hidden inside the garment or will be covered by the fabric you attach the elastic to. If the overlap will be visible, you can trim it close to the stitching, but this is purely for appearance.
Can I sew elastic to elastic by hand?
Yes, but it is slow and the seam is usually weaker than a machine-sewn seam. Use a ladder stitch or whip stitch and sew through both layers of the overlap multiple times. Machine sewing is faster and stronger, so it is the better choice if you have access to a sewing machine.