How this fence calculator works
Posts are the fence length divided by the post spacing, plus one to close the run. Each section between posts gets your chosen number of rails (two for fences up to 5 ft, three for 6 ft and taller), and pickets are the total length divided by picket width plus gap. Corners and gates each add a post — add them to the result manually.
Post depth and concrete
Set posts at least one third of their above-ground height into the ground, and below the local frost line — 2 ft (60 cm) is a common minimum for a 6 ft fence. Plan on about two 50 lb (25 kg) bags of concrete per post for a standard 8–10 inch hole; oversized holes or tall gate posts take more.
Picket spacing choices
A ½ inch gap is the classic picket look and lets air through; board-on-board (overlapping) privacy fences effectively use a negative gap — set the gap to -1 inch to approximate the overlap. For full-privacy solid fences, set the gap to 0. Pressure-treated pickets shrink as they dry, so tight-butted wet lumber ends up with small gaps on its own.