Before beginning to weave, you have to decide on the “sett” of the cloth being woven. This means the number of threads to the centimeter or inch of warp and weft. If you don’t do this your cloth might not work out nicely for it’s desired use.
One rule of thumb (and this isn’t set in stone for all types of weave) is to take the warp yarn and wrap it around a ruler, covering 3cm, ensuring that the threads just touch each other. Divide this number of threads by 3 to get the number per cm (eg 15 threads wrapped around ruler= 5 threads per cm). Don’t do this if you are using inches.
Half this number again to get the number of warp threads per centimetre (e/cm) or ends per inch (epi) for a balanced, plain woven cloth.
You need more warp threads then weft threads for a Warp-faced cloth so increase the epi by 2/3rds. Weft-faced cloth (like tapestries) need more weft thread and less warp thread.
Feel of Fabric
The sett has an effect on the feel of the fabric, the fewer epi will get you a more open, softer and more flexible cloth; the more epi the firmer, more rigid the cloth.