Introduction:
I’ve been beating around the bush recently with lots of topics all coming down to determining the sett for various projects. Sett is a large subject so this time I will be referring you to various previous posts. I think that way you can get a thorough picture of the topic.
Follow the links to the topics listed below:

1 – Read about what is sett and how diameters of yarns is important HERE
2 – Read about making your weaving easier. This is an introduction to a way of determining sett using the Ashenhurst Rule which will be in a following post HERE

3 – Here is the explanation and formula for Ashenhurst’s Rule. NOTE: Here he explains only the MAXIMUM SETT. You will probably never use that number because it will be denser than you want. Read the next installment about what to do for plain weave, twill, warp and weft face and purpose etc. HERE

4 – Ashenhurst Part Two: The previous post gave you a calculation that will give you the number of diameters, which will be used to determine the sett for a fabric. The reason you want to know the Ashenhurst number of diameters is that it’s his number that is used to make allowances for yarns, weave, shrinkage finishing, purpose (e.g. upholstery or sheer curtains, etc.). What you actually do is to calculate the maximum sett so that you can ten take a percentage of it to allow for different purposes of the cloth or types of yarns. For most “normal” weaving I use 80% of the maximum sett. You just use another % if you want something else. Read on.
This worksheet I made to make all this handy to use. You can see that first is calculating the maximum sett. Then taking the various percents of that figure for different weaves, purposes, etc. See that you would take 90% of maximum sett for upholstery and 50-60 percent for delicate fabrics.
5 – Good reasons to Use Ashenhurst’s 80% figure are given in this post HERE

6 – An example how to use the sett charts: You have a 5/2 pearl cotton that is 2100 yards per pound (ypp). You want to weave a twill, so you would look in the Twill Chart for 2050 yards/pound.
Then, going across that row, look for the purpose of the cloth you want to make.
If you want something very delicate, you would choose the 50% column and see that it is 14 EPI.
If, however, you wanted to make a pillow, you might choose the 80% number (22epi). This sett is what I recommend for “regular cloth”—what I use unless I want extra dense or delicate fabrics. Read more in my book Weaving for Beginners or THERE ARE MANY MORE sett charts in Winding a Warp & Using a Paddle. There are 14 pages of charts with hundreds of yarns and threads all calculated for you.

7 – Select the sett for purpose, width, yarn type HERE

8 – Read sett basics and Ashenhurst HERE