Article — Privacy Fence Calculator
Privacy Fence Calculator: Posts, Pickets, and Total Cost
A standard 6-foot wood privacy fence at 8-foot post spacing needs 14 posts, 39 rails, and about 210 pickets per 100 linear feet, plus 14 × 60-lb bags of concrete. Material cost runs $900-$1,300 in 2026 US prices for pressure-treated pine ($9-$13 per linear foot materials, $25-$50 installed). Cedar costs 30-50 percent more in materials but lasts twice as long. The standard formula: posts = ceil(length / spacing) + 1, pickets per 8-ft section = 16-17 at 1×6 lumber with 0.5-inch gap, rails per section = 2 for ≤5 ft height, 3 for 5-7 ft, 4 above 7 ft.
This calculator handles standard wood privacy fence layouts. Enter total length in feet, height (3-12 ft), post spacing (4-10 ft), and picket width and gap. It outputs posts, rails, pickets, concrete bags, plus material cost and cost per linear foot using your input prices.
Wood privacy fence basics
A privacy fence has three layered systems: posts (4×4 vertical members set in concrete), rails (2×4 horizontal members spanning between posts), and pickets (1×6 or 1×4 vertical boards nailed to rails for the privacy face). Picket gap determines privacy: 0 inches for full privacy, 0.5 inch standard, 1 inch for semi-private, 2 inches for shadow-box (transitions from solid privacy to airflow).
The standard 6-foot height balances privacy (blocks all sightlines of adults) with cost and code compliance. Most US municipalities cap residential privacy fences at 6 feet without a permit. 8-foot fences require permits and engineered wind-load designs. Below 4 feet the fence isn't really "privacy" — it shows everything.
Privacy fence posts and spacing
Standard post spacing is 8 feet on center. This matches the 8-foot length of 2×4 rails and 1×6 pickets sold at home centers, minimizing cutting waste. For windier sites or 8-foot tall fences, drop spacing to 6 feet — about 33 percent more posts but dramatically less rail and picket sag.
Post count = ceil(length / spacing) + 1. The +1 accounts for the closing end post. For a 100-foot fence at 8-foot spacing: ceil(100/8) + 1 = 13 + 1 = 14 posts. Posts are 4×4 pressure-treated pine, 8 feet long for a 6-foot fence (6 feet above grade + 2 feet buried + a few inches for trim). Set in concrete with 1 × 60-lb bag per post.
The 8-foot post spacing standard exists because pressure-treated 2×4 rails are 8 feet long. Stretching to 10-foot spacing means buying 10-foot rails (premium price) and accepting more sag. Shrinking to 6-foot spacing means more posts and more concrete but stiffer fence. The post spacing decision compounds: every foot of extra spacing requires roughly 33% more rail bending strength. Modern engineered fence designs use 10-foot spacing with welded steel posts because wood rails would sag too much.
Rails, pickets, and fence height
The rail count per section depends on fence height. Under 5 feet uses 2 rails (one near the top, one near the bottom). 5-7 feet uses 3 rails (top, middle, bottom). Above 7 feet uses 4 rails. The middle rails support the pickets at intermediate points, preventing cupping and bowing. Skip a middle rail and pickets twist over time, particularly in humid climates.
Picket count per section uses the formula: pickets = ceil(section width in inches / (picket width + gap)). For an 8-foot section (96 inches) with 5.5-inch pickets and 0.5-inch gap: 96 / 6 = 16 pickets per section. Across 13 sections of a 100-foot fence: 208 pickets. Most home centers sell pickets in bundles of 50 or 100; round up to the next bundle.
Privacy fence material cost
Per 100 linear feet of 6-foot pressure-treated fence in 2026 US prices: 14 posts at $14 each = $196; 39 rails (2×4×8) at $8 each = $312; 208 pickets (1×6×6) at $2.50 each = $520; 14 × 60-lb concrete bags at $5.50 each = $77; hardware (brackets, screws) about $130. Total materials: roughly $1,235 — about $12 per linear foot.
Cedar bumps the cost by 30-50 percent in materials: posts $20, rails $14, pickets $4. The same 100-foot fence in cedar runs $1,700-$1,900 in materials. Composite (Trex Seclusions, TimberTech, AZEK) runs $3,500-$5,000 in materials and is largely self-installing because the panels snap together — but the cost gets steep for big runs.
Posts (4×4×8 PT) 14 × $14 = $196Rails (2×4×8 PT) 39 × $8 = $312Pickets (1×6×6 PT) 208 × $2.50 = $520Concrete (60-lb) 14 × $5.50 = $77Hardware + screws ~$130Total materials ~$1,235 ($12.35/ft)Wood species and fence lifespan
Pressure-treated pine (the budget standard) lasts 15-20 years. The pressure treatment forces preservative deep into the wood, protecting against rot and insects. Western red cedar lasts 15-30 years naturally without chemical treatment — its heartwood contains natural oils that resist decay. Redwood is similar to cedar but more expensive and harder to find outside the West Coast.
Avoid untreated spruce-pine-fir (SPF) for any fence component touching the ground or atmospheric moisture. SPF in ground contact lasts 3-5 years before failure. Even untreated cedar can fail prematurely if the heartwood-to-sapwood ratio is wrong (sapwood has none of the natural preservative oils). For maximum lifespan, choose pressure-treated for posts and ground-contact rails, then any rot-resistant species for pickets above grade.
Fence permits and property lines
Most US municipalities require permits for any fence above 6 feet. Some cities require permits for any fence over 4 feet, particularly in front-yard locations. Always check before starting; a contractor can pull the permit on your behalf for $50-$150, a small fraction of project cost. Building without a permit risks tear-down orders, which are expensive and embarrassing.
Property line surveys are worth the $300-$600 cost before building a privacy fence. Stake the corners and run string lines along the legal property edge, then build inside that line by 3-6 inches. Building "on" the line creates ambiguity that becomes a problem when the property sells; building 1 foot inside the line creates a maintenance strip you can mow without trespassing.
Common privacy fence mistakes
The first mistake is undersizing posts. A 4×4 post is the minimum for a 6-foot fence; 6×6 posts are stronger but rarely needed. Cheaping out with 3×3 or 2×4 posts produces a fence that leans within 5 years. The second mistake is shallow post holes. Code minimum is 30 inches depth or below frost line, whichever is greater. Shallower posts heave in winter and lean in spring.
Fences built directly on the surveyed property line create maintenance access problems and shared-ownership ambiguity. Always offset 3-6 inches inside your line. This gives you mowing access without trespassing on the neighbor and avoids the "is it my fence or hers" disputes that surface when one or both properties change hands.
The third mistake is skipping the kickboard (rot board) at the bottom of pickets. Pickets touching dirt wick moisture into the wood and rot within 5 years. The fix: install a 2×6 horizontal board at the bottom, with pickets nailed to it sitting 1-2 inches off the ground. The kickboard rots first, then can be replaced cheaply.
- Posts formula = ceil(length / spacing) + 1
- Standard spacing = 8 ft on center
- Rails per section = 2 (≤5 ft), 3 (5-7 ft), 4 (>7 ft)
- Pickets per 8-ft section = 16-17 (1×6 with 0.5-in gap)
- Concrete = 1 × 60-lb bag per post
- PT pine material cost = $9-$13 per linear foot
- Permit threshold = typically 6 ft tall
- Post hole depth = 30 in or below frost line