Continuous Bias Tape Calculator: What Size Square to Cut
Enter the length of bias tape you need and the cut width of the strips: the calculator gives the side of the fabric square to cut for continuous bias tape, or the length your square makes.
1 yard = 36 in. Or enter the size of the project to bind below.
The one given by your pattern or your bias tape maker, before folding.
Bind a rectanglequilt, tablecloth, place mat
Extra length for joining the ends of the binding, per your method. In decimal inches (10 1/2 in = 10.5).
Fabric square to cut
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How the calculation works
Continuous bias: a fabric square is cut into two triangles, sewn back together into a parallelogram, then sewn into a tube offset by one strip width; a single long strip is then cut in a spiral.
Length made: area of the square ÷ strip width, minus one side of the square, used up by the one-strip offset when the tube is sewn (Fabrics-Store). A 14 in square and 1.5 in strips make 196 ÷ 1.5 − 14 ≈ 116 in.
Square to cut: the calculator solves the reverse equation (side² ÷ width − side = length needed), rounds the side up to the next whole inch, and shows the length that square actually makes.
Binding a rectangle: the length needed is the perimeter of the project, 2 × (width + length), plus the overlap you plan for joining the two ends.
Sources:
Sources consulted November 10, 2026
Limitations
- Trimming the angled ends removes a few more inches (Fabrics-Store): plan a margin, or round the square up by an inch or two.
- The seam allowances of the triangle seam and the tube seam are not deducted from the area.
- The cut width depends on the finished width you want and on how you fold it: use the one given by your pattern or your bias tape maker.
- Many quilters cut binding on the straight grain, in strips cut across the width of fabric (WOF): this calculator covers continuous bias only. The length needed (perimeter plus overlap) is the same either way.
Results are estimates. Always check your pattern's instructions and the product label or seller's information.
Frequently asked questions
What size square do I need for 3 yards of bias tape?
A 14 in square, with strips cut 1.5 in wide, makes about 116 in (14² ÷ 1.5 − 14), a little more than the 108 in in 3 yards. Wider strips need a larger square.
Why cut bias tape on the diagonal?
A strip cut at 45° to the grain stretches and follows curves (necklines, armholes, rounded corners) without puckering, unlike a strip cut on the straight grain.
How much binding do I need for a quilt?
The perimeter of the quilt plus the overlap for the join: for a 60 × 80 in quilt, 2 × (60 + 80) = 280 in, about 7.8 yards, plus that overlap.