How much continuous bias tape a fabric square yields.
Continuous-bias length \u2248 square area \u00f7 strip width.
The length of continuous bias tape that a square of fabric makes equals the area of the square divided by the width of the strip. An 18 inch square has an area of 324 square inches, so with 2 inch strips it makes about 162 inches, or 4.5 yards, of tape. Enter the size of the square and the strip width to see how much you will get.
Allow for losses, since the ends of the strip are trimmed and each seam uses a little. If you need an exact length, cut a slightly bigger square. A good estimate is a little less than the figure the calculator gives.
The width you cut depends on how you will fold the tape. For double fold bias tape, the strip is cut about four times the width of the finished tape, so a two inch strip gives a tape about half an inch wide when it is finished and folded.
Cut the square accurately and on the straight grain, since errors multiply along the strip. A bias tape maker makes the folding even, and pressing with steam sets the shape and keeps the tape from stretching out.