Actually if you just read the instructions, it should be very clear how long the final length will be:

  • Cut a wire to a given length. 
  • Tie a knot near the end (the knot eats up 2 cm of wire).
  • Cut 2 cm off of the tip of the wire.
  • THEREFORE  it  is  now  4 cm  shorter  than  the  original cut  length:



We use the same scheme for all versions of the Spiderbeam Yagi.  Therefore if you have any other version (i.e. 3-Band, Low Band, etc.), simply follow the same scenario:  Cut-Length minus 4 cm.