Bias Tape Calculator for Continuous Strips

You cut one big bias parallelogram, sew it into a tube with a one-strip offset, then cut around the tube in a spiral. That turns the whole square into one long continuous strip with very little waste.

A strip of width w and length L covers an area of w times L. The square supplies its full area, so the total strip length is the area divided by the width. This is the standard continuous-bias approximation and ignores the small losses at the ends.

It is a close upper estimate. Real yield is a little lower because of the trimmed end triangles and the seam used to form the tube, so cut a slightly larger square if you need an exact finished length.

For double-fold tape, cut about four times the finished folded width. For single-fold tape, cut about twice the finished width. Use the cut width here, not the finished width.

This tool assumes a square. For a rectangle, multiply its two side lengths to get the area, then divide by the strip width to get the same continuous-bias length estimate.