Linear mass density of a fiber can be reported in tex or yield.
Tex is defined in grams per kilometer (weight per distance)
Yield is defined in yards per pound (distance per weight)
1 yard = 0.914 meters
1 pound = 454.5 grams
number in Tex =
= 1 / ((number of yields) * 0.914 / (454.4 * 1000)) =
= (4.96 * 10^5) / (number of yields)
number in yields =
= (4.96 * 10^5) / (number in Tex)
