Posts equal linear feet divided by post spacing, plus one end post. For a 100-foot fence at 8-foot centers, that is 13 posts. Rails equal spans (posts minus 1) multiplied by rails per span; a privacy fence uses 2 rails per span and a 3-rail split-rail uses 3. Before digging, use the concrete bag calculator to find how many bags of fast-set concrete you need for the post holes.
A 150-foot privacy fence at 8-foot spacing needs 20 posts, 38 rails (19 spans × 2), and 327 pickets (1,800 inches divided by 5.5-inch boards). At $12 per post, $8 per rail, and $3 per picket, that totals about $1,525 in materials before labor. These counts assume no gates; each gate opening removes pickets but adds two gate posts.
Privacy fences use no gap between 5.5-inch boards, so picket count equals linear inches divided by 5.5. Picket fences leave a 3.5-inch gap between 3.5-inch boards, needing roughly half the pickets of a privacy fence. Board-on-board overlaps each picket by 1.5 inches so every board covers 4 inches instead of 5.5, adding about 27% more pickets versus standard privacy. If you are also decking or flooring nearby, the plywood calculator handles sheet counts for subfloors and decking in the same project.
Split-rail fences use no pickets at all, just posts and rails slotted through drilled holes. Two-rail uses the same post count as privacy but only 2 rails per span; three-rail adds a lower rail for horse or livestock enclosures. To measure your lot perimeter before buying materials, the square footage calculator converts property dimensions into linear feet.