Machine knitting yarns info

More of my class notes, assembled from various sourcesThese guidelines  were provided for knitting using Jaggerspun yarns. I have no affiliation with the company. I do still continue to use some of lines, and have a great appreciation for all their yarns. Their wool used to be the required fiber in my knit labs at RISD until students began to understand some of the basics in stitch construction. I have permission from the company to share content.

Some yardage references: 2/24 = approximately 5500 to 6700 yards per pound
3/15 = approximately 2650 yards per pound
2/15 = approximately 3670 yards per pound

A few more bits:
fixed length of yarn spun from a specified weight of the material
1’s 1 spinning
1’s Yorkshire woolen 256  yards per pound
1’s linen 300  yards per pound
1’s worsted 500-560  yards per pound  primary standard for wool and acrylic
1’s cotton 840  yards per pound
1’s    spun silk840 yards per pound
2’s mean that twice the above length of yarn was spun from one pound of raw material

yardage reference: the first number refers to the number of plies twisted together to form the yarn, the larger the second number, the thinner the spun strand; conversely the smaller the second number, the thicker the diameter of the strand
yardage may vary with plies depending on mill and country where yarn is spun
2/24  5500 to 6700 yards per pound
3/15  2650 yards per pound  (530)
2/15  3670 yards per pound   (489)

in cotton  the markings are reversed
3/2 Cotton 3 x 840 ÷ 2 = 1,260 yards/pound
20/2 Cotton 20 x 840 ÷ 2 = 8,400 yards/pound
one standard for hand knitting yarn: gauge is per inch, not for a 10 X 10 cm or 4 X 4 inch swatch
fingering = 5 or 6,  knits approximately at 8 sts/12  rows per inch
sport weight yarn = 3 or 4, knits approximately at 6 sts/8 rows per inch
worsted yarn = 2, knits approximately at 4 sts/ 6 rows per inch
3/15 machine knitting yarn: the second number by the first = 5, so this would knit at approximately the same gauge as fingering weight

stranding math
2 strands  2/24 = 4/24 = 6 = fingering weight
3 strands  2/24 = 6/24 = 4 = sport weight
4 strands  2/24 = 8/24 = 3 = heavy sport weight
5 strands  2/24 =10/24 = 2.4 = close to worsted
6 strands  2/24 =12/24 = 2 = worsted

for more information and convenient conversions  for use in machine knitting see

the American Craft Council standard yarn weight system  is included in their PDF on standards and guidelines for crochet and knitting