Calculating how much cording to use when making macrame items:

You'll need to calculate how long the length of your cording should
be.  Although most projects will give you the recommended measurements,
you should have some idea of how this measurement is reached.

The ends of cording should be 3 ½ to 4 times longer than the piece
you plan to make, however, since the cording is doubled in half for 
knotting it is measured 7 to 8 times longer than the amount needed. 
For example:  if the Macramé project will have a finished length of 1 yard
you'll want to measure your cording 7 to 8 yards from one end to the other. 
Then when each end is doubled for knotting it will be two ends, each end
being 3 ½ to 4 yards long.

Make sure that you measure the ends generously since you don't want
to run out of cording and have to add to the project.  It's much better
to have extra cording than it is to run out and add in an inconvenient place
in the design.