Bias tape finishes curved edges and hems without puckering or stretching
Bias tape is a strip of fabric cut at a 45-degree angle to the grain, which lets it bend around curves without bunching. When you fold it in half lengthwise and stitch it to an edge, it creates a neat, professional finish on armholes, necklines, sleeve cuffs, and quilt borders. The tape itself does the work — the diagonal cut gives it the flexibility that straight-grain binding cannot match.
You can buy bias tape ready-made in most fabric stores, or cut and press your own from any cotton fabric. The method is the same either way: pin the tape to the edge, stitch it down on one side, fold it to the back, and stitch it again from the reverse. The whole process takes minutes once you understand the sequence.
Key Takeaways
- Bias tape must be pinned with the raw edges aligned to the garment edge, then stitched with a quarter-inch seam allowance on the first pass.
- After the first seam, fold the tape to the back of the garment and pin it so the fold covers the first line of stitching.
- The second seam is sewn from the back side, catching the tape fold and securing it permanently in one pass.
- Corners and curves require you to stop stitching, pivot the tape, and resume — the bias cut handles the angle without pleats or gaps.
- Pressing the tape with an iron before and after stitching makes the fold crisp and the final edge lie flat.
What you need before you start
Gather bias tape (single-fold or double-fold, half-inch width is standard), a sewing machine, thread that matches the tape or the garment, pins, an iron, and scissors or a rotary cutter. If you are using ready-made tape, you need nothing else. If you are cutting your own, you also need a fabric square, a ruler, and a pencil or chalk.
Measure the edge you plan to bind by laying a measuring tape along it. Add two inches to that length to account for overlap at the seams and corners. If you are binding a neckline that measures 20 inches, cut or buy 22 inches of tape.
Press the tape with an iron on medium heat before you begin. This removes wrinkles and makes the fold crisp, so it sits flat against the garment when you pin it.
Pinning the tape to the garment edge
Lay the garment flat on your work surface with the edge you want to bind facing up. Open the bias tape so it is no longer folded — you should see a long strip with a crease down the middle. Align one long edge of the tape with the raw edge of the garment, right sides together. The crease should run parallel to the garment edge, about a quarter-inch away from it.
Pin the tape every two to three inches along the entire edge. At corners, stop pinning about a quarter-inch before the corner point and leave the tape loose — you will fold it at the corner after the first seam. For curved edges like armholes, pin more frequently (every inch) so the tape follows the curve without bunching.
Check that the tape is not twisted and that the garment edge is not stretched. If the garment fabric is puckering under the tape, unpin that section and smooth it out before re-pinning.
The first seam: attaching the tape to the front
Thread your machine with thread that matches the tape or blends with both the tape and garment. Set the stitch length to 2.0 or 2.5 millimeters — a standard length that will hold without creating a weak seam. Sew along the crease of the bias tape, keeping a quarter-inch seam allowance between the needle and the raw edges of both the tape and the garment.
Sew slowly around curves. Stop with the needle down every inch or so, lift the presser foot, and adjust the garment so the tape stays aligned. This prevents the tape from shifting and the garment from stretching. At a corner, sew to the corner point, stop with the needle down, lift the presser foot, and fold the tape at a 45-degree angle away from the corner. Lower the presser foot and continue sewing along the next edge.
When you reach the end, overlap the tape by half an inch with the starting point and trim the excess. Backstitch at the beginning and end of the seam to lock the thread.
Folding the tape to the back and pinning the second seam
Remove the garment from the machine and press the seam you just made with an iron. Fold the tape to the back (wrong side) of the garment so the fold of the tape covers the line of stitching you just made. The raw edge of the tape should now be hidden inside the fold. Pin the tape in place from the back, positioning the pins so they run parallel to the fold and about a quarter-inch from it.
On curved edges, the tape may not lie perfectly flat at first — this is normal. Smooth it gently as you pin, working in sections. The bias cut allows the tape to ease around the curve without pleats. If you see a small pleat forming, unpin that section, smooth the tape, and re-pin.
At corners, fold the tape at a 45-degree angle on the back side, just as you did on the front. The fold should be crisp and the tape should lie flat on both sides of the corner.
The second seam: stitching the tape from the back
Flip the garment over so the back is facing up and you can see the pinned tape. Sew along the fold of the tape, staying as close to the fold as possible without stitching into the garment itself. This seam will catch the fold and find the tape permanently. Use the same stitch length as the first seam (2.0 to 2.5 millimeters).
Sew slowly and check frequently that the needle is catching the fold of the tape. If the needle misses the fold on any section, that part of the tape will not be secured and may lift away from the garment later. If this happens, you can hand-stitch those spots with a ladder stitch or whip stitch after removing the garment from the machine.
Backstitch at the beginning and end. Press the finished edge with an iron on medium heat, pressing from the back side first, then the front. The tape should now lie flat and smooth on both sides of the edge.
Handling corners and curves without puckering
Corners require a fold on both the front and back of the tape. On the front, fold the tape away from the corner at a 45-degree angle before you resume stitching. On the back, fold it the same way. The diagonal fold uses the bias cut to its advantage — the tape bends without bunching because the grain is already at an angle.
Curves are easier than corners because you do not need to fold. Instead, pin the tape more frequently (every inch instead of every two to three inches) and sew slowly. The bias cut naturally eases around the curve. If you see a small pleat forming on the inside of a tight curve, stop, unpin that section, smooth the tape gently, and re-pin before continuing.
Armholes and necklines are the most common curved edges. These usually have a gentle curve, not a sharp one, so the tape will follow the shape without extra folds. Sleeve cuffs and quilt borders are often straight or have only slight curves, so they require the least adjustment.
Frequently Asked Questions
Can I use straight-grain binding instead of bias tape?
Straight-grain binding will pucker on curves because it does not stretch. Bias tape is cut at a 45-degree angle, which gives it the flexibility to bend around armholes, necklines, and other curved edges without bunching. For straight edges only, straight-grain binding works, but bias tape is the standard for most garment finishing.
What is the difference between single-fold and double-fold bias tape?
Single-fold tape is folded once lengthwise, so you open it and fold it yourself as you sew. Double-fold tape is already folded twice, so you just pin it and sew — it is faster and neater for beginners. Both work the same way; double-fold is straightforward pre-pressed and saves a step.
How do I fix a section where the tape did not catch on the second seam?
Remove the stitches in that section with a seam ripper, smooth the tape, re-pin it, and sew again. If you prefer not to remove stitches, you can hand-stitch the loose section with a ladder stitch or whip stitch, using thread that matches the tape. This is faster than re-machining and looks just as neat.
Do I need to press the tape before I sew it?
Pressing removes wrinkles and makes the fold crisp, so the tape sits flat and is easier to pin. It is not required, but it makes the work faster and the result neater. If your tape is already flat and wrinkle-free, you can skip this step.
What happens if I sew the bias tape with the wrong sides together?
The tape will be visible on the front of the garment instead of the back. If you notice this before you finish, remove the stitches and start over. If you finish and then notice, you can flip the tape to the correct side, re-pin, and sew the second seam again — the first seam will be hidden inside the fold.