Vinyl thinks in sections, not pickets
Unlike wood, vinyl fencing is ordered as finished <strong>6 or 8-foot sections</strong> with routed posts. Divide the run by the section length and round up — the last section gets cut down to fit, and the manufacturer's gate hardware fills the remainder. A 104-foot run in 6-foot sections is 18 sections: 17 full plus one trimmed.
Post types: count each
A vinyl run needs line posts between sections, a corner post at each turn, an end post at each terminating end, and a heavy gate post on each side of an opening. The section count gives you line posts; add the others from your layout sketch before ordering — routed posts can't be swapped after delivery.