Fence Calculator
Posts = perimeter ÷ spacing + 1
How Fence Material Calculations Work
Fence material counts start with the total perimeter in feet. For a rectangular 60 ft × 40 ft backyard, perimeter = 2 × (60 + 40) = 200 ft. Posts are spaced every 8 feet on center (industry standard): posts = ceil(perimeter ÷ spacing) + 1 = ceil(200 ÷ 8) + 1 = 26 posts. The extra post closes the fence line at the end.
Horizontal rails depend on fence height. Fences 6 ft and taller use 3 rails per section; shorter fences use 2. With 26 posts forming 25 sections, a 6 ft privacy fence needs 26 × 3 = 78 rail boards (or equivalent linear feet of top/bottom rail). Posts are typically 4×4 lumber set 2 ft deep in concrete footings.
Picket count uses picket width plus gap between pickets. A 3.5 in picket with 0.5 in gap covers 4 in (0.333 ft) per picket position. For 200 ft: 200 ÷ 0.333 ≈ 600 pickets. Panel-style vinyl fencing divides perimeter by panel width (usually 8 ft): 200 ÷ 8 = 25 panels. Gates are counted separately — a single 4 ft gate needs its own posts and hardware.
Corner and slope changes add complexity. Stepped fencing on hills shortens effective picket spans. Check local codes for maximum height (often 6 ft in backyards, 4 ft up front) and setback requirements before ordering materials. Pressure-treated posts rated for ground contact last decades longer than untreated lumber, and galvanized or stainless fasteners prevent rust streaks on cedar and pine pickets.
| Perimeter | Posts (8 ft spacing) | Pickets (4 in span) |
|---|---|---|
| 100 ft | 14 | ~300 |
| 150 ft | 20 | ~450 |
| 200 ft | 26 | ~600 |
| 300 ft | 39 | ~900 |
Enter perimeter, fence height, post spacing, and picket dimensions to get post, rail, picket, and panel counts. Pair with the concrete calculator for post footing volumes.
Examples
| Example | Result |
|---|---|
| 200 ft perimeter, 6 ft high, 8 ft post spacing | 26 posts, 78 rails, ~600 pickets |
| 100 ft perimeter, 4 ft high | 14 posts, 28 rails |
| 150 ft perimeter, 6 ft, 3.5 in pickets | 20 posts, ~450 pickets |
| 80 ft perimeter, panel fencing | 11 posts, 10 panels |
| 250 ft perimeter, 6 ft high | 32 posts, 96 rails |
| 120 ft perimeter, 5 ft high | 16 posts, 48 rails |
| 60 ft perimeter, 4 ft picket fence | 9 posts, ~180 pickets |
Frequently asked questions
Eight feet on center is standard for wood privacy fencing. Heavier ranch rail or livestock fencing may span 10–12 ft with larger posts.
Six-foot privacy fences typically use three horizontal rails — top, middle, and bottom — for structural rigidity against wind.
Walk the fence line with a measuring wheel or plot corners on a map. Sum each straight segment. This calculator accepts total perimeter as one input.