All that can be done is to give a rough guide based on the two most important of these, viz. size of canvas mesh and nature of rug (i.e. whether smooth-faced or pile).

Taking smooth-faced rugs first, the larger the mesh, the thicker must be the amount of wool carried in the needle to hide the canvas threads and therefore the thicker and heavier will be the layer of wool covering on both the front and back of the finished rug.

Again the stitch used also has an effect on the weight of wool required, mainly owing to the pro­portion of wool used up at the back of the canvas.

For example, rice stitch uses a lot more wool than Soumak stitch.