How to Calculate Fabric for Bias Tape
Bias tape is cut at a 45-degree angle to the fabric grain. This diagonal cut gives the tape stretch, which lets it curve around necklines, armholes, and quilt edges without puckering. The trade-off: diagonal cuts use more fabric than straight cuts.
The key measurement is the cut strip width. For double-fold bias tape, the cut width is 4 times the finished width. A 1/2-inch finished tape needs 2-inch-wide strips. This accounts for the two folds plus a small amount of overlap.
Bias Tape Fabric Requirements
| Finished Width | Cut Width | 120" of tape | 240" of tape |
|---|---|---|---|
| 1/2" (single fold) | 2" | 1/4 yard | 3/8 yard |
| 1" (single fold) | 4" | 3/8 yard | 1/2 yard |
| 1.5" (double fold) | 6" | 1/2 yard | 5/8 yard |
| 2" (double fold) | 8" | 5/8 yard | 7/8 yard |
| 2.5" (double fold) | 10" | 3/4 yard | 1 yard |
These estimates assume 44-inch fabric. Wider fabric (58-60") yields more tape per cut, so you'll need less yardage.
Continuous Bias Tape Method
The continuous method lets you make long strips of bias tape from a single fabric square without individual strip joining. Here's the overview:
- Cut a fabric square (calculator gives you the size)
- Cut the square diagonally into two triangles
- Sew the triangles together on the straight grain with a 1/4" seam
- Mark parallel lines at your cut width across the fabric
- Form a tube by offsetting one line, sew the edge
- Cut along the spiral line — one continuous strip
For 120 inches of 2-inch finished bias tape, you need about a 16-inch fabric square. The continuous method is faster than cutting and joining individual strips for anything over 60 inches.
FAQ
How do I know how much bias tape a quilt needs?
Add up all four sides of your quilt plus 10-12 inches for corners and overlap. A 60" x 80" quilt needs about 280 + 12 = 292 inches. Round up to 300 inches. Use the quilt binding calculator for exact measurements.
Single fold vs double fold — which do I need?
Double fold is the standard for quilt binding and garment edges. The tape folds in half, wrapping around the fabric edge with finished edges on both sides. Single fold is used for facings, casings, and internal seam finishes where one side won't be visible.
Can I use non-woven fabric for bias tape?
You can, but the bias stretch won't be as pronounced. Woven cotton is the standard because the 45-degree cut maximizes stretch. Knit fabrics already stretch, so you'd just cut straight strips instead.
Related Tools
- Quilt Binding Calculator — calculate binding for your quilt
- Fabric Yardage Calculator — how much fabric for your project
- Quilt Size Calculator — dimensions and fabric for any quilt