Yarn count systems

To measure yarns, it is not possible to measure their diameter because the cross-section is so easily deformed, so we have to resort to distinguishing them by yarn count.

Yarn counting is based on knowing two measurements:

By relating these two measurement we get values called:

Direct method

The direct method, called the fixed length, variable weight method, is given by the ratio of the weight divided by the length (T=W/L).
This method is commonly used for all yarns made with continuous fibres
(silk, rayon, nylon etc.)

Indirect method

The Indirect method, also called the fixed weight, variable length method,
is given by the ratio between the length and the weight (N=L/W). The count by this
method (N) is commonly used for all yarns made with discontinuous fibres (wool, cotton, rayon staple etc.). The most commonly-used indirect counts are:

There are also the English carded wool count, the English combed wool count,
and the English flax and hemp count.