Fence Calculator

How to Use This Calculator (Step by Step)

1. Enter total fence length — Measure the full linear feet of your fence line, including all sides. If you have multiple runs, add them together.
2. Set fence height — Standard heights are 4 feet (picket, pool), 6 feet (privacy), and 8 feet (tall privacy). Height determines rail count and post size recommendations.
3. Choose post spacing — 8 feet on center is standard. Use 6 feet for high-wind areas or heavy fences. The calculator defaults to 8 feet.
4. Select fence type — Privacy (no gap), picket (with gap), rail (no pickets), or board-on-board (overlapping pickets for full coverage on both sides).
5. Set picket width and gap — Standard 1x6 pickets are 5.5 inches actual width. The gap defaults to 0 for privacy fences and 2.5 inches for picket fences.
6. Add gates — Enter the number of gates and width per gate. Each gate uses two extra posts and reduces the picketed length.
7. Enter corners and end posts — Specify the number of corners and end posts for accurate post counts. Corners may need extra bracing.
8. Review results — The calculator shows posts, rails, pickets, concrete bags, rail linear feet, and recommended post size. Enter material prices to see total cost.

How the Calculations Work

The fence calculator follows standard construction formulas used by fencing contractors. Here is the math behind each component:

• Sections: Total fence length ÷ post spacing, rounded up. For a 100 ft fence at 8 ft spacing: 100 ÷ 8 = 12.5, rounded up to 13 sections.
• Line posts: Sections + 1 = 14 line posts for the example above. Additional posts are added for gates (2 per gate), corners, and extra end posts.
• Rails per section: Fences 5 feet and taller get 3 rails (top, middle, bottom). Fences under 5 feet get 2 rails (top and bottom).
• Total rails: Sections × rails per section. Rail linear feet = Sections × post spacing × rails per section.
• Pickets (privacy/picket): (Fence length − gate widths) × 12 ÷ (picket width + gap) = raw picket count. Multiply by (1 + waste%) for the final count. For a 100 ft privacy fence with 5.5" pickets, no gap, and one 4 ft gate: (100 − 4) × 12 ÷ 5.5 = 209.5 pickets, plus 10% waste = 231 pickets.
• Pickets (board-on-board): Same formula but uses effective coverage (picket width − overlap). With 1.5 inch overlap on 5.5 inch pickets: effective coverage = 4 inches. Pickets = (Fence length − gates) × 12 ÷ 4 × (1 + waste%).
• Concrete bags: 2 bags per post is the default. This accounts for a 12-inch diameter hole, 24–30 inches deep, which is consistent with typical values found in ACI concrete guidance for residential fence post footings.
• Post size recommendation: Fences 8 feet and taller use 6×6 posts. Everything under 8 feet uses 4×4 posts. Gate posts always use 6×6 for added strength.

Example: A 150 ft privacy fence at 6 ft height, 8 ft post spacing, one 4 ft gate, 5 corners, with 10% waste: Sections = 19. Line posts = 20. Gate posts = 2. Corner posts = 5. Total posts = 27. Rails per section = 3. Total rails = 54. Rail linear feet = 456. Pickets = (150 − 4) × 12 ÷ 5.5 × 1.10 = 350. Concrete bags = 54.

Measuring Tips

• Measure the total linear feet of your fence line along the property boundary
• Account for corners, gates, and changes in elevation
• Mark post locations with stakes before purchasing materials
• Check for underground utilities before digging post holes — call 811 at least 48 hours before digging
• Add 10% extra for waste, cuts, and mistakes
• Measure along the actual ground contour, not on a map — slopes add length
• For sloped terrain, decide between stepping the fence (level sections) or racking (following the slope) before calculating pickets

Fence Type Guide

Choosing the right fence type depends on your goals — privacy, decoration, pet containment, or pool safety. Each type has different material requirements and aesthetic characteristics.

Privacy fence: Pickets installed edge-to-edge with no gap. Provides complete visual screening. Best for backyards and property boundaries. Use 5.5" wide (1×6) or 3.5" wide (1×4) pickets.

Picket fence: Decorative pickets with consistent gaps between them. The classic front-yard fence. Gap width is typically equal to picket width for a balanced look, but can be customized.

Board-on-board: Overlapping pickets that provide full privacy from both sides. Uses more pickets than a standard privacy fence (roughly 50% more) but looks finished on both sides — ideal for shared property lines with neighbors.

Rail fence: Horizontal rails between posts with no pickets. Common on rural properties and for decorative boundaries. Uses the fewest materials of any fence type.

Common Mistakes to Avoid

• Not calling 811 before digging: Hitting an underground utility line is dangerous and expensive. Call at least 48 hours before you plan to dig. It is free and required by law in most states.
• Shallow post holes: Posts that are not buried deep enough will lean and eventually fail. In frost zones, holes must extend below the frost line (36–48 inches in most of the US). The general rule is bury at least one-third of the total post length.
• Using non-treated lumber for posts: Posts in contact with soil must be pressure-treated or naturally rot-resistant species like cedar or black locust. Standard SPF lumber will rot within 3–5 years in ground contact.
• Skipping concrete footings: While some fence styles can use tamped gravel or dirt backfill, concrete provides the most secure and long-lasting anchoring. It is worth the extra $2–$3 per post in concrete bags.
• Forgetting to slope concrete away from posts: Concrete should crown slightly above ground level and slope away from the post to shed water. Flat or recessed concrete traps water against the post, accelerating rot.
• Not planning for gates: Gates need wider posts (6×6), extra concrete, and heavy-duty hinges. Account for gate posts and hardware in your material order, and allow at least 3–4 feet for a walk gate or 8–10 feet for a vehicle gate.
• Ignoring wind load: A 6-foot solid privacy fence acts like a sail in high winds. In exposed areas, consider alternating picket-and-gap designs, shorter heights, or 6-foot post spacing instead of 8 feet.

Tips for Best Results

• Use pressure-treated lumber or cedar for ground contact posts
• Set posts in concrete for maximum stability and longevity
• Use galvanized or stainless steel fasteners to prevent rust and staining
• Install a gravel base in post holes for drainage before pouring concrete
• Check local building codes for height and setback requirements
• Stain or seal wood fences within 2–4 weeks of installation for best protection
• Space pickets using a custom spacer block for consistent gaps — a simple scrap of wood cut to your gap width saves hours of measuring
• Pre-cut all pickets and rails before starting installation for faster assembly
• Use a post level (the kind that straps to the post) to ensure posts are plumb in both directions while the concrete sets

Pro Tips for Contractors

• When quoting fence jobs, always include a site visit to verify property lines, slopes, and access. Slopes of more than 12 inches over 8 feet may require stepped sections, which change the picket and rail calculations.
• Use the board-on-board option when clients want privacy on both sides of the fence. It avoids the "good side / bad side" dispute with neighbors and typically commands a 40–50% price premium over standard privacy fence.
• For gate posts, always use 6×6 lumber set in extra-deep concrete (minimum 36 inches). A 4-foot walk gate with hardware weighs 80–120 lbs and a vehicle gate can weigh over 200 lbs — the posts need to handle that moment load without leaning.
• Order 15% extra pickets for privacy fences and 10% for rail fences. The waste factor covers end cuts, defects, and the inevitable pickets that split during nailing.
• Pre-build gate frames in the shop using diagonal bracing for squareness. Field-built gates tend to sag within the first year. Use metal gate hardware with adjustable tension rods for long-term serviceability.
• Include post caps in every quote. They cost $2–$5 per post but extend post life by years by preventing water from entering end grain — the most common point of rot failure in fence posts.

Fence Cost Guide

Material costs per linear foot vary by fence type. Add 30–50% for professional installation labor. These prices reflect typical US averages for wood fencing.

Prices are approximate US averages (2024–2025). Gates add $150–$500 each. Lumber prices can fluctuate significantly.

Post Depth & Concrete Guide

Proper post depth and concrete footing are the most critical factors in fence longevity. The rule of thumb: bury one-third of the total post length, and make the hole diameter three times the post width. These guidelines are consistent with general residential construction practices and are informed by typical values found in ACI concrete guidance for residential footings.

In frost zones, holes must extend below the frost line (36–48 inches in most of the US).