Twist Per Inch - Determining How Many Twists Per Inch

Determining How Many Twists Per Inch

The number of twists per inch can, in plied yarns, be determined by counting the number of bumps in one inch, and divide by the number of singles (the strands plied together to make the yarn). If the picture to the right, for example, was of an inch of 2 ply yarn, then the number of twists per inch would be 6 divided by 2, or three, as there are six bumps, and it is a two ply.

While this method works very well with plied yarns, singles don't have bumps to count. One way to determine the tpi for a single is to add a contrasting color fibre when spinning it, and then count the number of times the contrasting fibre has wrapped around the yarn. Another method is to measure an inch of yarn, and untwist it, counting how many full revolutions it takes until there is no twist left. This can be done by inserting two paper-clips into the yarn, at an inch apart, thus making it easier to count a full revolution. A less precise method is to allow the single to ply against itself: the resulting two ply yarn is about half the number of twists per inch of the single. Thus one can roughly find the number of twists per inch for the single, or one can use the doubled back yarn as a measure.

With yarn that is both thick and thin, than it is best to count over several inches and average them. This is because the number of twists per inch will tend to vary from the thin and thick sections.