How to use the bias tape length calculator
- Choose Rectangle and enter its width and length, or choose A length I measured and enter the total edge.
- Enter the extra for joins and overlap. The 12 inches shown is an example.
- Enter the cut width of the strip and the fabric width.
- Read the tape length and the fabric to buy. Add a package length in More options to count ready-made packages.
Formula
edge = 2 x (width + length) for a rectangle
tape length = edge + extra for joins and overlap
strip area = tape length x cut width
fabric length = strip area / fabric width x (1 + waste)
Dividing the strip area by the fabric width is an estimate of the length of fabric you need. Bias cutting uses a bit more because of the triangles at the ends.
Binding a 40 by 60 inch throw
The edge of a 40 by 60 inch rectangle is 2 x (40 + 60) = 200 inches. With 12 inches extra the tape is 212 inches, or 5.89 yards. Cut 2 inches wide, the strips cover 424 square inches. On 44 inch fabric that is 9.64 inches of length, or 10.6 inches with 10% waste, which is 0.294 yard. Rounded up to the next 1/8 yard, buy 0.375 yard.
For ready-made tape sold in 3 yard packages, 212 inches is 5.89 yards, so you need 2 packages.
Choosing the strip width
The cut width depends on the tape you want and how it is finished. Fold-over tape is cut at about four times its finished width, while a single-fold facing needs less. Use the width from your pattern or tutorial. A wider strip needs more fabric, and the calculator scales the fabric with the width.
Bias strips are cut on the diagonal grain, which makes them stretch around curves. For a straight edge such as a quilt, straight-grain strips are often used instead and need less fabric.
Related sewing tools
For a quilt edge cut on the straight grain, use the Quilt Backing and Binding Calculator. The Fabric Yardage Calculator covers general yardage, and the Elastic Length Calculator sizes elastic for a waist or cuff. For a table covering, see the Tablecloth Size Calculator.
Assumptions and limits
- The fabric estimate is based on area, so it ignores the exact way you cut and join strips.
- The extra length is your allowance for joins, corners and the overlap where the ends meet.
- The waste percentage is an example you can change.
- Fabric is rounded up to the next 1/8 yard for buying.
Frequently asked questions
How much bias tape do I need for a quilt?
Measure the whole edge and add extra for corners, joins and overlap. A 40 by 60 inch quilt has a 200 inch edge, so with 12 inches extra you need 212 inches.
How much fabric do I need to make bias tape?
Multiply the tape length by the cut width to get the area, divide by the fabric width, and add some for waste. For 212 inches cut 2 inches wide on 44 inch fabric, buy 0.375 yard.
How wide should I cut bias strips?
Use the width your pattern or folding tool calls for. Fold-over tape is commonly cut about four times its finished width, but check your method.
What if I buy ready-made bias tape?
Enter the package length in More options. The page divides the tape length by it and rounds up to whole packages.