Fence Calculator
Calculate materials needed for building a wooden privacy or picket fence: 4x4 posts, 2x4 horizontal rails, pickets, gate framing, concrete bags, and screws.
Calculation Results
Total pressure-treated 4x4 vertical posts (includes dedicated gate hinge posts).
Number of pressure-treated 2x4 horizontal backer rails.
Total individual cedar or treated pine pickets (includes gate facing).
Fast-setting concrete mix (calculated at 2 fifty-pound bags per post hole).
Pounds of 1-5/8" coated exterior screws (approx. 200 screws per pound).
How This Calculator Works
Estimate your fence materials with these quick steps:
- Measure the Perimeter: Enter total linear footage of the fence line.
- Select Fence Height: 6 feet is standard residential privacy; 4 feet is typical for decorative front yards.
- Select Post Spacing: 8 feet is standard; use 6 feet in coastal or open windy areas.
- Add Gates: Specify number of walk gates to adjust posts and deduct openings.
- Review Bill of Materials: Get exact 4x4 posts, 2x4 rails, pickets, 50lb concrete bags, and exterior screws.
Formula & Calculations
Fence material takeoffs calculate linear spans into post sections, structural rail lines, and infill pickets:
1. Post & Section Spacing
Posts divide the perimeter into equal bays (standard 8ft or 6ft in high-wind regions):
Posts = ceil((Fence Length - Gate Openings) / Spacing) + 1 + Dedicated Gate Posts
2. Rail Sizing by Height
- 4-Foot Fence: 2 horizontal 2x4 rails per section (top and bottom).
- 6-Foot Privacy Fence: 3 horizontal 2x4 rails (top, middle, and bottom) to prevent picket bowing.
- 8-Foot Fence: 4 horizontal 2x4 rails.
3. Picket Quantities
Pickets = ceil(Fence Length / (Picket Width + Gap)) × (1 + Waste / 100)
For a solid 6ft privacy fence with 5.5" pickets and 0" gap, budget approximately 2.18 pickets per linear foot.
Step-by-Step Calculation Examples
Residential Backyard Privacy Fence (120ft Line, 6ft Tall)
Full perimeter 6ft solid privacy fence with 1 walk gate and 8ft post spacing.
- length: 120
- fence_height: 6
- post_spacing: 8
- picket_style: 5.5
- picket_spacing: 0
- gates_count: 1
- waste: 5
- posts: 17
- rails: 48
- pickets: 275
- concrete_bags: 34
- picket_screws_lbs: 9
Frequently Asked Questions
How deep should fence posts be buried in the ground?
Standard building practice requires burying fence posts at least one-third (1/3) of their total length, or a minimum of 24 inches for a 6-foot fence. In cold northern climates with deep frost lines, posts should be buried 36 to 48 inches deep to prevent frost heaving.
How many bags of concrete do I need per fence post?
For a standard 4x4 post in an 8-inch to 10-inch diameter hole dug 24 to 30 inches deep, budget two 50 lb bags of fast-setting concrete (or 1.5 bags of 80 lb standard concrete) per post hole.
Should I space fence posts 6 feet or 8 feet apart?
8 feet on-center is the economical industry standard for residential privacy fences because 2x4 rails come in 8ft lengths. However, in regions with severe wind storms or heavy snow drifts, 6-foot post spacing provides 40% higher resistance against storm blowouts.
How many rails should a 6-foot privacy fence have?
A 6-foot wooden privacy fence should always have three 2x4 horizontal backer rails (top, middle, and bottom). Installing only two rails on a 6ft fence will cause the pickets to cup, twist, and pull away from the framing within 1 to 2 years.
Should pickets touch the ground?
No. Fence pickets should always be installed 1.5 to 2 inches above the soil line. If pickets touch ground dirt or wet mulch, they will wick up moisture, leading to premature rot, mold, and termite infestation.
What screws or nails are best for fence pickets?
Use 1-5/8 inch ceramic-coated exterior screws or hot-dipped galvanized ring-shank nails. Never use standard drywall screws or ungalvanized finish nails, as the copper chemicals in pressure-treated wood will corrode them within months.