The metric count of yarn characterizes the thickness of the yarn and the yarn is the number of meters in one gram. Number of yarn can be calculated by dividing the length of thread on a reel, expressed in meters, the coil mass in grams. Thus, the yarn is thicker so it metric number is smaller. If the yarn is composed of several strands, the number is written as fractions (eg, 32 / 2), while the denominator indicates the number of strands twisted together, and the numerator – the number of separate threads. Knitting products often combine several strands.

In this scenario, the resulting yarn is called total. For example, when two threads 10 / 2, their total number will be 10 / 2:2 = 2,5. The thickness of the yarn in the 'tex' numerically is equal to the number of grams of one kilometer of yarn (g / km). If the yarn is twisted several strands, the thickness of the designated product. One of the factors determines the thickness of a single component filaments, the other – the number of twisted yarns, for example 100h2.

To determine the thickness of the yarn is the ratio between the thickness of the yarn in the 'tex' and its metric number: T = 31 tex x 2 – 32 / 2 T = 42 tex x 2 – 24 / 2 T = 64 tex x 2 – 16 / 2 T = 100 tex x 2 – 10 / 2 T = 110 tex x 3 – 9 / 3 T = 165 tex x 2 – 6 / 2 wool introduced the concept of conditional mass. This mass of skein of wool yarn under normal (conditioned) conditions, ie at a certain humidity and temperature. This concept was introduced because the wool is well absorbs moisture, and when the external conditions is easily gives it to the environment. When soaking wet weight of wool increases and decreases in returns. Weight skein of wool yarn, weighted at home may differ slightly from the conditional mass declared on the label of a coil, because the degree of humidity and temperature in the room are different from normal (conditioned). when buying yarn for knitting a single article must also pay attention to the batch number: skeins of the same color must be from the same batch, otherwise the thread may vary in hue, that will be noticeable in the finished product. This and more can be found at 'Knitting'