They express how much a certain thread weight measures when compared to other threads across the scale. They are called inverse just because the larger the number, the thinner the thread which seems illogical at first but is in fact simpler once you understand more of the finer points of spinning.

Also known as reverse or direct systems, it applies to fibers of limited length such as cotton, wool, etc.

The number is both higher and smaller is the diameter, in this weight system is fixed and the length is variable.

The formula is:

  • N'K L/ P
    • No. Number
    • Constant Ko
    • L. Length
    • P. Weight

Now we will look at how this is applied to actual measurements. Numberings or thread title for this system is as follows for both the English numbering system and the metric:


First we will look at the metric system to see how it is defined, many students of spinning prefer this system over the English as it is easier to work the numbers mentally. But in the end it is due to personal preference.

  • The metric number expresses the thousands of meters per kilo of each cape, followed by the number of capes.
  • The metric system is the most common of all the systems described.
  • For example, a thread consisting of 2 ends of 60,000 m/kg each is expressed as Nm 60/2.
  • To know the footage that has a kilogram of thread, simply divide the footage of a cape by the number of ends that form it.
  • For example, a 60/2 would have 30 thousand m/kg and a 60/3 would have 20 thousand m/kg.

English Number

And now the English numbering system with the metric measurements included for comparison.

  • The definition is the number of 840-yard skeins (768.08 m) weighing 1 lb (English pound 451.59 g)
  • It is enough to know that you have to multiply by 1.7 to go from the English system to the metric.
  • This numbering has always been the usual for cotton.
  • For example the cotton yarn Ne 30/1, which is an Nm 50/1