CalcCoverageHow many fence posts do I need?
A fence is built in sections between posts. Divide the run by your post spacing, round up to whole sections, and the posts are always sections + 1 — every run has a post at both ends.
Sections = round up(length ÷ spacing) · Posts = sections + 1 · Rails = sections × rails per section
Example: a 100 ft run at 8 ft spacing needs ceil(100 ÷ 8) = 13 sections, so 14 posts and 26 rails at 2 per section. With standard pickets (5.5 in wide + 0.5 in gap), it takes 200 pickets — 220 with 10% extra for warped and split boards.
The picket count
Standard pickets are 5.5 in wide and are installed with about a 0.5 in gap, so each picket “uses” 6 inches of fence line — a simple 2 pickets per foot. Wider gaps for a more open look use fewer: change the plan, and pickets per foot = 12 ÷ (picket width + gap, in inches).
| Run at 8 ft spacing | Posts | Rails (2/section) | Pickets |
|---|---|---|---|
| 40 ft | 6 | 10 | 80 |
| 80 ft | 11 | 20 | 160 |
| 100 ft | 14 | 26 | 200 |
| 160 ft | 21 | 40 | 320 |
Posts are set in concrete: about two 50-lb bags of mix per standard post hole is a fair planning figure (deeper or wider holes take more). Gates need their own heavier posts and hardware — count gate posts separately from this run.