Our standard cable Spacing is 3″ on center running the length of each post.
To calculate your cable requirement you must measure from the top of your deck or bottom rail to the bottom of your top rail, then divide that number by the cable spacing (3″) and subtract 1.
Example: 30 inches between deck and top rail: 30 / 3 =10 and 10-1= 9. The requirement is 9 runs of cable.