Bias tape is a strip of fabric cut at 45 degrees to the grain with the long raw edges pressed under. The bias cut is the whole point: woven fabric has almost no stretch along the grain but stretches on the diagonal, so bias tape curves smoothly around a neckline or an armhole where a straight-grain strip would buckle.
Two forms, and the difference decides how you use it:
- Single fold: both raw edges pressed to the centre. Used as a facing, turned to the inside so it does not show, or stitched flat as a trim.
- Double fold: single fold, then folded again down the middle, with one side slightly wider. Used to bind an edge, wrapping it so the tape shows on both sides.
Sizes are quoted by the finished width. Quarter inch for fine edges and small curves, half inch for most necklines and armholes, and one inch for quilt binding and heavier edges. Cut your own fabric strips at four times the finished width for double fold.
Bias tape and bias binding are the same product. Binding usually implies the double-fold type used to bind an edge, and tape is the general term.
What Is Bias Tape?
Bias tape is a narrow strip of fabric cut along the bias, meaning at 45 degrees to both the lengthwise and crosswise grain, with the long raw edges pressed under.
The bias cut is the entire point. Woven fabric has almost no stretch along the grain but a useful amount of give on the diagonal, so a bias strip can curve around a neckline, an armhole or a scalloped edge and lie flat. The same strip cut on the straight grain would ripple on the outside of a curve and pucker on the inside. Our guide to cutting fabric on the bias explains the mechanics in more detail.
Bias tape versus bias binding
They are the same product. “Bias tape” is the more common term in the US, “bias binding” in the UK. Some sewists use “binding” specifically for tape applied to enclose an edge and “tape” for the strip itself, but the packet in the shop is the same thing either way.
Single Fold vs Double Fold
This is the distinction that matters most when buying, and the packet labels are not always clear.
| Single fold | Double fold | |
|---|---|---|
| Construction | Both raw edges folded to the centre | Single fold, then folded again down the middle |
| Folds when opened flat | Two | Three, one slightly off-centre |
| Main use | Facings, casings, decorative trim, hemming | Enclosing a raw edge |
| Applied | Usually opened out and stitched flat | Wrapped over the edge and stitched through |
| Finished width | Same as the stated size | Half the single fold width |
One detail catches people out constantly: on double fold tape the two halves are deliberately made slightly uneven, with the back a fraction wider than the front. That is not a manufacturing fault. Apply it with the narrower side facing you and the wider side underneath, and when you stitch from the front you automatically catch the back. Put it on the wrong way round and you will miss the underside in places.
Bias Tape Sizes and What to Use Them For
Packaged bias tape comes in a standard set of finished widths. The number on the packet is the finished width, not the width of the strip before folding.
| Finished width | Typical use | Cut width if making single fold | Cut width if making double fold |
|---|---|---|---|
| 1/4 inch | Lingerie, doll clothes, baby garments, fine detail | 1/2 inch | 1 inch |
| 1/2 inch | Quilt binding, lightweight garments, the default choice | 1 inch | 2 inches |
| 3/4 inch | Heavier quilts, bags, aprons | 1 1/2 inches | 3 inches |
| 1 inch | Bold decorative binding, home furnishings | 2 inches | 4 inches |
| 2 inches | Statement trim, heavy home decor | 4 inches | 8 inches |
The arithmetic is worth memorising because it is the thing people get wrong when cutting their own: single fold, cut twice the finished width. Double fold, cut four times the finished width.
If you only ever buy one size, buy 1/2 inch double fold. It handles quilt binding, garment edges and most home projects.
How to Use a Bias Tape Maker
A bias tape maker is a small metal funnel that folds the strip for you as you feed it through, so you press instead of measuring. They cost very little and they are the single biggest time saver in this whole process.
- Cut your strip on the bias at the correct width for the size of maker you have. A 25mm maker needs a 25mm-finished strip, so cut at twice that.
- Trim one end to a point. This lets the strip start into the funnel.
- Feed the pointed end into the wide end of the maker and push it through with a pin until it emerges from the narrow end with both edges folded in.
- Pin the emerging end to your ironing board.
- Pull the maker slowly along the strip with one hand while following immediately behind it with a steam iron in the other. The fabric exits already folded; the iron sets it.
- For double fold, fold the finished single fold tape in half lengthwise and press again, keeping one side a fraction wider.
Go slowly. Rushing the pull is how you get folds that wander. A shot of steam and a firm press as you go gives creases that survive handling.
How to Sew Bias Tape onto an Edge
For double fold tape enclosing a raw edge, the method that gives a clean finish on both sides:
- Open out one fold of the tape and pin its right side to the right side of your fabric, raw edges aligned.
- Stitch along the crease line you just opened.
- Press the tape away from the garment, then fold it over the raw edge to the back.
- From the front, stitch in the ditch or edgestitch close to the fold. Because the underside is slightly wider, this catches it automatically.
Going around curves and corners
On an outside curve, gently stretch the tape as you pin. On an inside curve, ease it in without stretching. This is exactly what the bias cut is for, so let the fabric do the work rather than forcing it.
For a mitred corner, stitch to the seam allowance distance from the corner, backstitch, fold the tape up at 45 degrees, then back down aligning with the next edge, and resume stitching. Our quilt binding tutorial walks through mitred corners step by step, and the same technique applies to any bound edge.
Joining strips and closing the loop
Join bias strips with a diagonal seam rather than a straight one. A diagonal join spreads the bulk across the width instead of stacking it in one place, which matters on a binding that will be folded double. Press the seam open and trim the dog ears.
Buying vs Making Your Own
| Shop-bought | Homemade | |
|---|---|---|
| Cost | Low per packet, adds up over a project | Cheaper, especially from scraps |
| Fabric choice | Limited colours, usually poly-cotton | Any fabric you own |
| Quality | Often thin and stiff | Matches your garment fabric |
| Time | None | 30 to 45 minutes for several metres |
| Best for | Utility work, quick repairs, casings | Visible binding on a garment you care about |
My rule is simple: if the binding will be seen, make it. Packaged tape is usually a thin poly-cotton that will not match a good garment fabric in weight or drape. If it is a casing hidden inside a waistband, buy it.
The full method is in how to make bias binding.
Frequently Asked Questions
What is bias tape used for?
Enclosing raw edges on necklines, armholes and hems, binding quilts, making casings for elastic or drawstrings, adding decorative trim, and finishing seams inside unlined garments. It is also the neatest way to finish a curved edge that a facing would fight.
What is the difference between single fold and double fold bias tape?
Single fold has both raw edges pressed to the centre. Double fold takes that and folds it in half again, so it wraps over a raw edge. Single fold is generally opened out and stitched flat as a facing or casing; double fold encloses an edge.
How wide should I cut fabric for bias tape?
Twice the finished width for single fold, four times for double fold. For 1/2 inch double fold tape, cut 2 inch strips.
Do I need a bias tape maker?
No, but it pays for itself immediately. Without one you fold and press by hand against a ruler, which works and takes several times longer. Our guide to choosing sewing tools covers where it sits in priority against other kit.
Can bias tape be cut on the straight grain?
You can cut strips on the straight grain and they are sometimes sold that way as “straight grain binding”. They work on straight edges. They will not curve smoothly around a neckline or armhole, and they will ripple if you try.
What fabric is best for making bias tape?
Lightweight woven cotton is the standard choice: quilting cotton, lawn, poplin or shirting. Avoid anything thick, since the tape ends up four layers deep at the fold, and avoid knits, which do not need the bias cut and will not press crisply. See quilting fabric for suitable options.
Final Thoughts
Bias tape is a small thing that carries a lot of finish. Learn the two-times and four-times rule for cutting, buy a 1/2 inch tape maker, and remember to put the narrow side of double fold tape face up so your topstitching catches the back.
Once you are comfortable binding an edge, French seams and quilt binding are the natural next finishing techniques to add.
