Free calculator · continuous bias binding
Enter how much binding you need and your strip width — get the exact fabric square to cut, how much tape it yields, and the finished single- and double-fold widths. A hem helper measures circle skirt hems for you.
The continuous method
Instead of cutting and joining dozens of short strips, you sew a single square into a tube and cut it in one spiral. Here is how 20" of fabric becomes about 200" of tape.
Cut the square the calculator gives you and cut it once along the diagonal into two triangles.
Place the triangles right sides together on a straight-grain edge and sew a 1/4" seam. Press it open.
Draw lines parallel to the long bias edges, one strip width apart — 2" for the default.
Bring the short edges together with the lines offset by one strip, sew into a tube, then cut along the line in one continuous spiral.
The 5% extra in the formula covers the seam and the offset at the ends of the tube.
Single vs double fold
Fold widths
Fold both long edges to the centre for single fold — half the strip, 1" from a 2" strip. Fold it again for double fold — a quarter, 1⁄2" — which wraps a raw edge and shows on both sides.
Where to use it
Each row opens the calculator with the length and strip width already filled in.
Circle skirt hem
A 28" waist, 22" full circle skirt has a 166 1⁄4" hem. With 5% extra that is 175" of 2" strips — a 20" square, yielding 200".
Neckline & armholes
A neckline or armhole needs a short, narrow tape that bends tightly. 30" of 1 1/2" strips — enough for a neckline plus joins — needs only a 7" square and yields 32 5⁄8".
Steam-press the tape into a curve that matches the neckline before you pin it; it lies flat without stretching the neck edge.
Quilt binding
A 50" × 60" throw has a 220" edge; add 10" for corners and the join and you need 230" of 2 1/2" binding — one 25" square, yielding 250".
Straight-grain binding is fine for square corners; bias binding wears longer on the folded edge and is required for scalloped or rounded quilts.
Worked examples
Worked example
Result
Result
The square grows with the square root of the length: about 1.7× the tape needs only a 29" square instead of 20".
The area of the square equals the area of the tape (length × width). For the default: √(180 × 2 × 1.05) = 19.4" → 20", and 20"² ÷ 2 = 200.0" of tape.
Tips
Lightly starch and press the square first — bias edges stretch easily once cut.
Use a long quilting ruler and a fine chalk or pencil line so the spiral cut stays even.
Feed the strip through a bias tape maker and press as it comes out for perfectly centred folds.
Steam the tape into a curve before stitching it to a hem or neckline — no ripples.
Get the exact hem circumference from the circle skirt calculator or the hem helper above.
Start stitching 6" in from the end so you have room to join the tape neatly.
The hem of a full circle skirt is 2π × (waist radius + length). A 28" waist and 22" skirt has a hem of about 166 1⁄4", so plan for around 175" of tape.
For 2" strips, a 9" square makes about 40 1⁄2" — a yard with a little to spare.
Fabric cut at 45° to the grain stretches and bends, so the tape follows curves without puckering.
Cut 2" strips. Single fold is half the strip width and double fold a quarter, so 2" gives 1" single fold or 1/2" double fold.
Add the four sides and about 10" for corners and the join. A 50" × 60" throw needs 230"; with 2 1/2" strips that is a 25" square.
Yes — cut separate 45° strips and join them with diagonal seams. It works for short lengths, but takes more seams and fabric than the continuous method.
Enter the length and strip width — get the square size, the tape it yields and the fold widths in seconds.
