To calculate the finished length of your Twist interchangeable knitting needle, multiply the needle tip length by 2, and add the cable length. For example, An 8″ (20 cm) cable length will make a 16″ (40 cm) circular needle when 4″ (10 cm) tips are attached. A 22" (55 cm) cable length will make a 32" (80 cm) circular needle when two 5" (1