[HNW] How do I figure thread amount?

[Christine Huse]

Hola!

I have been given a task of making a new herald's book for our Barony.  
Our Herald would like me to find out which would be better. Re-create it 
in wool? Or use a new thread (either silk or cotton).  He wanted to know 
how much it would cost.

I have no idea how to calculate how much thread I will need.  Does any 
know how I can calculate the thread usage for a particular project?

Maria