How to Join Two Pieces of Bias Tape

A 45° diagonal seam is the cleanest way to join two loose pieces of bias tape because it spreads the seam bulk along the tape instead of creating a thick ridge across it. Open folded tape before joining it, cross the ends with right sides together, sew the diagonal, then trim and press the seam. Use a different measuring method when you are closing the last gap in binding that is already sewn around a quilt, garment, or other project.

Why Bias Tape Uses a Diagonal Join

Bias tape is a strip cut diagonally across the fabric grain, which gives it enough flexibility to curve around necklines, armholes, rounded embroidery hoops, and shaped edges. That flexibility is useful, but it also means the tape can stretch or twist while you handle it.

A diagonal join helps in two ways:

The seam allowance is distributed along the tape rather than stacked straight across it.
The finished join bends more smoothly around curves than a perpendicular seam.

“Bias tape” can mean a single-fold strip, double-fold tape, or a flat strip you plan to press into binding. The joining method is the same in principle: open any folds, sew the tape as a flat strip, then press the folds back into place.

How to Join Two Loose Pieces of Bias Tape

Gather matching thread, fabric scissors, an iron, straight pins, and a sewing machine. If you are joining tape made from different fabrics, test that both fabrics tolerate the same pressing temperature before you press the finished seam.

Choose the setup that matches where you are in the project.

Your Situation	Best Method	Result
You have two separate lengths of tape or binding	Open the folds and make a diagonal splice	One longer continuous strip
You are piecing strips before making bias tape	Join the flat strips diagonally, then press the tape	A long strip ready to fold
You have already sewn binding around most of an edge	Measure and join the two remaining tails	A continuous finished binding loop

Step 1: Open and Cross the Tape Ends

Unfold both ends completely so you are working with flat fabric rather than trying to sew through the folded edges.
Lay one tape end horizontally, right side up.
Place the other end across it so the right sides face each other and the two strips form a cross.

For its own bias binding, Owl and Sewing Cat’s joining instructions use a 90° angle for the tape ends. Do not pull either strip taut as you position them.

The outer corners of the crossed strips should give you a diagonal path across the overlap. Before you sew, make sure the tape will form one straight, untwisted length after the seam is opened.

Step 2: Mark and Test the Diagonal Seam

Draw a line from one outer corner of the overlap to the opposite outer corner.
Pin along that line.
Fold the strips as though the diagonal seam were already sewn.

The marked line should produce a continuous strip, not a V shape, a loop, or a twist. If it does not, remove the pin and reverse the direction of the diagonal.

A 45° diagonal seam is the usual joining line for bias strips. The exact direction matters more than which corner you begin from.

I use straight pins at the crossed center and near each end of the marked line because they keep the stretchy bias edges from shifting while I check the layout.

Step 3: Sew the Join

Set the machine for a regular straight stitch with matching thread.
Use the middle, or center, needle position for the clearest view of the marked line; confirm the available center setting with your sewing machine’s needle-position control.
Stitch directly along the marked diagonal, removing pins as you reach them.
Secure the stitching at each end.

Use the middle needle position and place the diagonal stitching where the pressed fold lines meet. Those crease lines are useful guides when the join is pressed open.

Step 4: Trim, Press, and Refold the Tape

Trim the excess fabric from the seam, leaving about 3/16 inch (0.5 cm) beyond the stitch line. Owl and Sewing Cat uses this approximate trimming allowance for its own bias binding; check the joining directions for your particular binding if they specify a different finish.
Press the seam allowance open.
Refold the tape along its original creases and press it flat again.

Run your fingers along the refolded tape. The join should lie flat without a hard bump. Your longer piece of bias tape is now ready to attach.

How to Join the Final Ends of Attached Binding

Use the open-and-cross method for loose lengths of tape, but measure the overlap before joining the final two tails of binding already attached to a project.

This is the method to use when you have nearly finished binding a curved edge and need to close the remaining opening neatly.

Stop stitching before the two binding tails meet, leaving enough unsewn space to handle them comfortably.
Trim the left-hand binding tail straight across at a 90° angle.
Keep the small piece you cut off. Lay it against the cut edge of the attached binding tail as a spacer.
Lay the other binding tail over the spacer. Mark the second tail at the point that is the width of the folded binding plus 1 inch beyond the first cut edge.
Trim the second tail at that mark.

For example, you measure the actual folded binding width at the remaining opening, then add 1 inch to determine where the overlapping tail is cut. This gives room for the diagonal seam and lets the binding close without a gap or a bulky overlap.

Next, open both tails flat. Place them right sides together in a crossed arrangement and test the diagonal before stitching. Sew the diagonal seam, trim the seam allowance, press the seam open, and refold the binding.

Lay the joined section against the project edge before continuing. It should fill the opening without puckering or pulling. Finish stitching the remaining binding to the edge, wrap or fold it to the opposite side as your project requires, and stitch the final section closed.

Fix Common Bias Tape Joining Problems

The Tape Forms a V Shape or Twist

The diagonal was sewn in the wrong direction. Unpick the seam, press the tape flat, and cross the ends again with right sides together.

Before restitching, fold the pieces into their finished position without sewing. A wrong join creates an angle, twist, or closed loop.

The Join Is Bulky

A bulky join usually comes from sewing folded tape together, leaving too much seam allowance, or pressing the seam to one side.

If the tape still feels thick, check that no folded edge was caught inside the seam.

The Fold Lines Do Not Meet

The tape may have shifted while it was pinned or sewn. This is especially common with narrow tape or slippery fabric.

Unpick the join if the mismatch is noticeable on the finished side. Reposition the opened tape so the pressed creases meet at the diagonal stitch line, then stitch slowly along the marked line.

The Binding Is Too Short When Closing the Final Gap

The second tail was cut without enough overlap for the diagonal seam. The solution is usually to replace or extend that tail with another piece of binding, joined as a loose strip before you close the final opening.

Measure from the cut end using the actual width of the folded binding plus 1 inch. Measuring the binding at the opening matters because homemade binding and store-bought binding can have different folded widths.

Check the Join Before Attaching the Tape

A quick inspection now prevents a noticeable join on a finished edge. Check that:

The seam feels flat.
The tape is smooth after pressing.
The binding does not pull the project edge when laid in place.
The join is positioned away from a highly visible spot when your project allows it.

When making several strips for a larger project, join the loose lengths before you begin attaching the tape. This lets you press, inspect, and correct each seam on a flat work surface instead of struggling with a partly bound quilt, garment, or stitched piece.

Choose the loose-strip method when you need more length, or the measured-tail method when you are closing binding already attached to a project.

Frequently Asked Questions

Is There a Difference Between Bias Binding and Bias Tape?

Bias tape is the general name for a fabric strip cut on the bias, while bias binding usually refers to bias tape used to cover and finish a raw edge. Both may be single-fold, double-fold, homemade, or store-bought. In everyday sewing instructions, the terms are often used interchangeably.

How Do You Bind a Seam With Bias Tape?

Open one folded edge of the bias tape and place it right sides together with the seam allowance or raw edge. Stitch in the fold line, press the tape away from the seam, wrap it around the raw edge, and topstitch the folded edge in place. This encloses the seam allowance for a tidy finish inside garments, bags, and textile projects.

How Do You Sew Double-Fold Bias Tape?

Double-fold bias tape is sewn by opening one fold, stitching along that fold, then wrapping the tape around the raw edge so the other folded edge covers the first line of stitching. Stitch close to the outer folded edge to secure both sides. Sewing it in two passes gives more control than trying to catch both edges in one pass.

Can You Use Bias Tape on Curves?

Yes, you can use bias tape on curves. Handle it gently while sewing so you do not stretch it longer or distort the edge you are binding. Bias tape is particularly useful on curves because the diagonal grain lets it bend more readily than straight-grain tape. Handle it gently while sewing so you do not stretch it longer or distort the edge you are binding.