Bias tape follows curves because the grain runs diagonally—but only if you stretch and guide it correctly
Sewing bias tape to a curved edge works because the diagonal grain of bias tape has natural give that straight grain does not. But that stretch only helps if you manage the tape as it feeds under the presser foot. The core technique is to hold slight tension on the tape as it approaches the needle, ease it around the curve, and let the presser foot pull it through—never push. Most puckers and gaps happen because the tape is either fed too fast or held too tight.
The curve itself matters. A gentle curve (like the neckline of a straightforward dress) is forgiving. A tight curve (like an armhole or a circle) demands more attention and smaller stitches. The sharper the turn, the more you have to slow down and adjust the tape by hand as you sew.
Key Takeaways
- Bias tape stretches along its length because the grain runs at 45 degrees, which lets it bend around curves without bunching.
- Pin the tape to the fabric before sewing, placing pins every inch or so, and remove them as you approach the needle.
- Hold the tape under gentle tension as it feeds toward the needle, then ease it around the curve instead of pushing it through.
- Use a shorter stitch length (1.5 to 1.8 mm) on tight curves so the tape has more anchor points and cannot slip.
- Press the tape flat after sewing each section so it settles into the curve and does not bunch when you fold it to the back.
Prepare the tape and mark the curve before you sew
Start with bias tape that is already folded and pressed—single-fold or double-fold both work, though double-fold is faster because one edge is already folded. Unfold the tape completely and lay it flat. On the fabric, mark the curve with a pencil or chalk line if it is not already cut. The line should be the finished edge of your garment or project.
Pin the unfolded bias tape to the right side of the fabric, with the crease of the tape aligned to your marked line. Place pins every inch along the curve, perpendicular to the edge. On a tight curve, use more pins—every half inch is not too many. The tape should lie flat against the fabric at each pin point; if it buckles or gaps between pins, adjust the pins until it sits smooth.
Sew the first side of the tape with the presser foot on the fabric
Set your machine to a stitch length of 1.5 to 1.8 mm for curves, or 2 mm for gentle curves. A shorter stitch gives the tape more anchor points and prevents it from shifting. Thread your machine and lower the presser foot with the needle positioned just inside the crease of the bias tape, on the fabric side.
Begin sewing slowly. As you approach the curve, hold the tape under light tension with your left hand (the hand that feeds the tape toward the needle) and use your right hand to guide the fabric so the tape stays aligned to the edge. Do not push the tape through—let the presser foot pull it. If the tape starts to bunch or gap, stop with the needle down, lift the presser foot, adjust the tape and fabric, and continue. Removing pins as you sew prevents them from catching the tape and throwing off your line.
On a very tight curve, you may need to stop every few stitches and make small adjustments. This is normal and produces a better result than trying to sew through without stopping. Press the tape flat with an iron after you finish the first side, especially on curves where the tape may have shifted slightly.
Fold the tape to the back and pin before the second pass
Once the first side is sewn, fold the tape to the back of the fabric so it wraps the raw edge. The folded edge of the tape should cover the line of stitches you just made. Pin the tape to the back side, again placing pins every inch and removing them as you sew. On a curve, the tape may want to bunch on the back side even if it looked smooth on the front—adjust the pins until the tape lies flat.
If the tape is not covering the stitches evenly, the tape may have shifted during the first pass. Unfold it, check the alignment, and re-pin before folding again. A few minutes spent pinning correctly saves the frustration of sewing a second line that does not catch the tape edge.
Sew the back side with the tape underneath
Position the fabric so the back side faces up and the tape is underneath. Lower the presser foot with the needle positioned just inside the fold of the bias tape, catching the tape and the fabric layers below. Sew slowly, using the same short stitch length as the first pass. Guide the tape with your left hand and the fabric with your right, letting the presser foot pull rather than pushing.
On a curve, the tape on the back side may have more fullness than the front because the back of the curve is longer than the front. If the tape starts to bunch, stop and gently smooth it out before continuing. A few small tucks are normal on tight curves and will not be visible from the front once the garment is worn.
Press and trim after both sides are sewn
Once both sides are sewn, press the entire edge with an iron set to the heat appropriate for your fabric. Press from the front side first, then flip and press from the back. The heat and pressure help the tape settle into the curve and blend with the fabric. If any tape extends beyond the edge of the fabric, trim it with scissors or a rotary cutter.
Check the front and back for gaps or puckers. Small gaps at the very edge can be caught with a hand-stitched ladder stitch if they bother you, but they are usually not visible once the garment is finished. Puckers usually mean the tape was fed too fast or held too tight on the first pass—they are hard to fix after sewing and are better prevented by slowing down.
Adjust your technique for very tight curves
Armholes, necklines with sharp angles, and circular edges demand extra care. Use a stitch length of 1.5 mm or even 1.2 mm so the tape has maximum grip. Consider using a walking foot if your machine has one—it feeds the tape and fabric at the same rate and prevents the tape from shifting on tight curves.
On a very tight curve, you may need to stretch the tape slightly as you sew the first side. Hold the tape under gentle tension with both hands, letting the presser foot pull it through. This pre-stretches the tape so it does not bunch when you fold it to the back. Test this on a scrap first—too much stretch will cause the tape to pucker, and too little will leave gaps.
Frequently Asked Questions
Why does my bias tape pucker on curves?
Puckers usually happen because the tape is fed too fast or held too tight as it approaches the needle. Slow down, use a shorter stitch length, and let the presser foot pull the tape instead of pushing it. On the second pass, make sure the tape is pinned flat to the back before sewing—bunching on the back side often shows through to the front.
How do I keep bias tape from gapping on the inside of a curve?
Gaps on the inside of a curve mean the tape was not stretched enough on the first pass. Try holding the tape under light tension as it feeds toward the needle, or use a walking foot to control the feed rate. Pin more frequently (every half inch) so the tape cannot shift between pins. Press after the first pass to help the tape settle.
Can I use a single-fold bias tape on curves?
Yes. Single-fold tape works the same way as double-fold—unfold it, pin it to the marked line, sew the first side, fold it to the back, and sew the second side. Single-fold tape is thinner and may be easier to manage on very tight curves, but it requires more pressing to keep the fold crisp.
What stitch length should I use on a gentle curve versus a tight curve?
Use 2 mm for gentle curves like a straightforward neckline. Drop to 1.5 to 1.8 mm for armholes and tighter curves. For very tight curves like a circle or a sharp corner, use 1.2 to 1.5 mm. Shorter stitches give the tape more anchor points and prevent slipping.
Should I use a walking foot for bias tape on curves?
A walking foot helps on tight curves because it feeds the tape and fabric at the same rate, preventing the tape from shifting. If your machine has one, it is worth trying on a test piece. On gentle curves, a regular presser foot works fine if you guide the tape carefully.