First things first, yarn weight chart what do they do for me? Can you believe yarn weight chart do not have to do with how much the yarn weighs. Can you believe that??? When we are talking about yarn weight we are referring to how thick the strand of yarn is. Why is it important to consider yarn weights you ask. Because if you’re going to crochet and want to substitute a yarn, you will need to find a yarn that is similar weight to what was used in the pattern. For example lets say a pattern calls for med weight 4 yarn and you decide to use a super bulky size 6 yarn you project is going to turn out HUGE! Same as if you would say use a fingerling weight yarn size 2 your project is going to turn out super small compared to the written pattern which called for size med weight 4 yarn. That is why it is so important to use same weight yarn called for in pattern.
Yarn ply has nothing to do with yarn weight. It has to do with how many strands are twisted together to make the yarn. Some yarns are 1 ply and some are 4 ply.
So let say you have yarn that has no label so how do you find the weight of the yarn you ask. Yarn weight refers to the thickness of the yarn strand. One way to determine yarn weight is to look at the number of wraps per inch. How do you do this method well you wrap yarn around a ruler so that the strands sit next to each other. Then count the number of strands that fit in a 1 inch space. My favorite go to places for help in crochet is Craft Yarn Council
You need to check out my other resources you can find HERE
Source: Craft Yarn Council’s www.YarnStandards.com
Have a wonderful day crocheting!