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Results — 100 ft Privacy Fence
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Fence Building Guide 2026
How to Calculate Fence Posts
The number of fence posts equals the number of spans plus one. For a 100-foot fence with 8-foot post spacing: 100 ÷ 8 = 12.5 spans → 13 spans rounded up → 14 posts. Always round spans up, then add 1. Gate openings require two extra posts each (the gate frame posts are typically 4×6 or steel).
How to Calculate Fence Pickets
Picket count = total fence length in inches ÷ (picket width + gap). For a 100-foot solid privacy fence with 5.5" actual pickets and 0" gap: (100 × 12) ÷ 5.5 = 218.2 → 219 pickets. Add 10% waste for cuts, bad boards, and future repairs. Our calculator handles this automatically for any picket width and gap combination.
Post Hole Depth — The 1/3 Rule
Set posts with at least 1/3 of their total length underground. For a 6-foot fence with 8-foot posts: minimum 2.67 feet in the ground, round up to 36 inches. In frost-prone areas (most of Canada, northern US), posts must go below the frost line — 48 to 72 inches in Zone 4-5 climates — or use a frost-free footing design with a concrete bell at the base.
How Many Rails Do You Need?
A standard 6-foot fence uses 3 rails: one at the top, one in the middle, one near the bottom. A 4-foot fence can use 2 rails. An 8-foot fence should use 3–4 rails. Rail length = post spacing (typically 8 feet). Total rails needed = number of spans × rails per span.
Concrete Per Post Hole
Use this formula: Volume (ft³) = π × (radius²) × depth − post volume. For a 10-inch hole at 36 inches deep with a 4×4 post: ≈ 1.36 ft³ of concrete = about 2 bags of 60lb Quikrete. Our calculator does this math automatically. For Quikrete Fast-Setting, you can pour the dry mix directly in the hole and add water — it sets in 20–40 minutes.
Wood vs. Vinyl vs. Cedar — 2026
Pressure-treated pine ($8–$14/lf installed materials) is the most affordable option, lasts 15–25 years with staining. Western Red Cedar ($12–$20/lf) is naturally rot-resistant, holds stain better, and is lighter. Vinyl ($18–$30/lf materials) never needs painting and lasts 20–30 years but can crack in extreme cold. Composite fence ($25–$45/lf) mimics wood grain with minimal maintenance. The labor cost is similar for all materials — typically $15–$25/lf for installation.