Purchasing too much yarn feels like a waste of money.  But the even worse scenario is purchasing too little and not being able to match the dye lot!!!!  See the Best Method Rule and the Rule of Thumb below.  Neither is an exact science, so you will need to make the final decision for yourself.  I hope this information will help you make that decision.

The general rule of thumb for coverage is 1 yard per 1 square inch, adding 10% more yarn to accommodate errors and changing threads.  This method does not address the stitch used or the mesh size of the canvas.   

Each 1/4 pound hank of Waverly yarn has approximately 160 yards.
Each knot of Waverly yarn has approximately 8.5 yards.  

Example:  Project size 10" x 10" = 100 square inches.  
Yardage needed is 100 * 1.1 = 110 yards
Purchase:  1 hank with about 50 yards remaining or 13 knots with about 1/2 yard remaining   

Waverly is a 3 ply yarn, meaning each strand can be sepatated into 3 plies.  The number of plies used depends upon the mesh size of the canvas:

2 ply - 10 count mesh 
1 ply - 13/14 count mesh
PC#3 - 13/14 cound mesh
PC#5 - 18 count mesh

 In terms of wool, one strand of our Waverly wool is meant for 13/14 mesh canvas. Two strands work on 10 mesh. Pearl cotton #3 is intended for use with 13/14 mesh canvas whereas Pearl Cotton #5 should be used on 18 mesh canvas. Four strands of embroide