To sew elastic directly to fabric, cut the elastic shorter than the edge it goes on, divide both into quarters, pin the quarter marks together and sew with a zigzag while stretching the elastic until it lies flat against the fabric between the pins. Then fold the elastic to the inside and stitch a second time from the right side, still stretching, so the edge keeps its stretch. There is no casing and nothing to thread through: the elastic becomes the waistband or the edge, which is why this method is standard on knit skirts, leggings, pyjama shorts and underwear.
What do you need to sew elastic directly to fabric?
- Knitted or woven elastic, not braided. Braided elastic narrows when stretched and loses recovery once it is stitched through; it belongs in a casing. Knitted elastic stays the same width under tension and can be sewn through as often as you like. For a waist, 2 to 4 cm (3/4 to 1 1/2 in) wide is usual; for leg and arm openings, 6 to 10 mm (1/4 to 3/8 in).
- A stretch or ballpoint needle, 80/12 or 90/14, on knits; a universal needle on a woven edge.
- Polyester all-purpose thread. Cotton thread snaps when the seam is stretched.
- A zigzag or three-step zigzag stitch. A serger can also attach elastic, and a coverstitch or twin needle finishes the second pass nicely, but a basic machine with a zigzag does the whole job.
- Pins or clips, a tape measure and chalk for the quarter marks.
How much shorter than the fabric should the elastic be?
The elastic is always shorter than the edge, otherwise it has nothing to pull in. How much shorter depends on where it goes.
- Waist: your waist measurement minus 5 to 8 cm (2 to 3 in) for a knit waistband, closer to minus 5 cm for firm, wide elastic. Pin the loop around your waist before you sew: it should hold a skirt up without leaving a mark.
- Leg openings and necklines: about 10 percent shorter than the edge, so 0.9 times the opening. On a deeply curved leg opening, the back section wants more pull than the front; cut the elastic 10 percent shorter for the front half and 20 percent shorter for the back half, and mark where they meet.
- Sleeve hems on a blouse: the wrist or arm measurement plus 1 to 2 cm (3/8 to 3/4 in), so it slides over the hand without digging in.
The elastic length calculator runs these numbers for you, and a sewing guide that lists notions will usually state the cut length; Sewly's guides give it for each pattern and waist option.
How do you sew elastic directly to a waist, step by step?
This is the fold-over method used on most pull-on knit garments, worked on a finished tube: side seams already sewn, top edge raw.
- Make the loop. Overlap the ends of the elastic by 1.5 cm (5/8 in) and zigzag across the overlap twice. Check it is not twisted.
- Quarter-mark both. Fold the elastic loop in half and mark the folds, then fold the marks together and mark the two new folds. Do the same on the garment's top edge, starting at the center front and back; on trousers, the side seams are usually two of the four marks.
- Pin the elastic to the wrong side of the garment with its top edge level with the raw edge of the fabric, matching the four marks. The fabric between each pair of pins is longer than the elastic: that is the point.
- Sew the first pass along the lower edge of the elastic with a zigzag 3 mm wide and 2.5 mm long, or a three-step zigzag 5 mm wide and 1.5 mm long. Hold the work with one hand in front of the needle and one behind, stretch the elastic until the fabric lies flat between the two pins, and let the feed dogs move the fabric. Stretch the elastic, never the fabric.
- Fold the elastic to the inside so the fabric wraps around it and only fabric shows on the outside. The first row of stitching is now hidden inside the fold.
- Sew the second pass from the right side, through fabric, elastic and fabric, with the needle 2 to 3 mm (1/8 in) below the lower edge of the elastic. Stretch as before. A zigzag, a three-step zigzag or a twin needle all work; a straight stitch will snap the first time the waist is pulled on.
- Steam the waistband without pressing down. The heat shrinks the elastic back to its cut length and evens out the gathers.
For leg openings and underwear edges, the method is the same but the elastic is often sewn to the right side with its decorative edge pointing in toward the garment, then flipped to the inside so the picot edge peeks out.
Tip: Sew the first pass with the elastic on top and the fabric underneath. You can see the elastic edge, and the feed dogs ease the longer fabric layer for you.
What are the most common mistakes with sewn-on elastic?
- Braided elastic. It twists, narrows and stops recovering once you stitch through it. Check the label or stretch a piece: if it gets noticeably narrower, it is braided.
- Stretching too much or too little. Too much and the waist ends up tight and ruffled; too little and it sags. The pins tell you how far to stretch: the fabric between them lies flat, not gathered.
- Pulling the fabric instead of the elastic. The fabric stretches out of shape, the elastic does not pull in enough, and the waist grows.
- Sewing with a straight stitch. The thread has no give. Use a zigzag, a three-step zigzag or a twin needle on both passes.
- Cutting the elastic to your body measurement. Elastic that has not been shortened does nothing. Always test the loop around you before sewing.
- Bunching the ease in one place. Four marks are the minimum; on a wide waist, use eight.
When should you sew elastic directly instead of using a casing?
Sew the elastic on when the fabric is a knit, when bulk matters (leggings, underwear, a slip), and when you want the waistband to stay evenly gathered without the elastic twisting inside a tunnel. The stitching holds the elastic flat forever.
Use a casing on woven fabric, with wide braided elastic, and when you may want to replace the elastic later: a casing keeps the elastic loose, which is kinder to a non-stretch fabric and easy to open. The elastic waistband casing guide covers that method, and elastic waistband methods compared sets the two side by side with the exposed elastic and the drawstring options. For a first project in this technique, a pair of knit pull-on shorts has a short waist seam and forgiving fabric.