Calculate Materials for Your Fence Project
Building a fence is one of the pricier DIY projects—materials for 150 feet of privacy fence can run $2,000-4,000. Ordering short means delays and extra delivery fees. Ordering excess means returning heavy lumber or storing it. This fence calculator determines exactly how many posts, rails, pickets, and bags of concrete you need based on your fence length, style, and height.
Understanding Fence Components
Posts: The structural backbone. Typically 4×4 treated lumber, spaced 6-8 feet apart. Buried 2-3 feet deep (⅓ of above-ground height for stability).
Rails: Horizontal supports connecting posts. Privacy fences use 2×4 rails (2-3 per section). Most fences need top and bottom rails; tall fences (6+ feet) need a middle rail.
Pickets: Vertical boards creating the fence face. Spacing varies: tight for privacy (½" gaps), wider for semi-privacy (1-2" gaps), decorative (3-4" gaps).
Concrete: Each post needs a concrete footing. Standard is 8-10" diameter hole, 2-3 feet deep. One 50 lb bag of concrete per post is typical.
Measuring for Your Fence
1. Measure total fence length: Use a long tape measure or measuring wheel. Walk the fence line and account for slopes, corners, and curves. Add 10% for irregular terrain.
2. Mark corners and gates: Corner posts need extra bracing. Gate openings need two posts close together (gate width + 4 inches). Subtract gate width from total fence length.
3. Determine post spacing: 8 feet is standard for most fences. Use 6 feet on slopes or for very tall fences (6+ feet). Closer spacing = stronger fence but more posts and concrete.
4. Calculate post count: Divide fence length by post spacing, then add 1. A 100-foot fence with 8-foot spacing needs 13 posts (100 ÷ 8 = 12.5, round up to 13 sections = 14 posts, minus 1 for the gate).
Installation Pro Tips
Set corner posts first: These are your reference points. Make them perfectly plumb and at the exact height. String a line between corners to align intermediate posts.
Use a post hole digger, not a shovel: Clamshell-style post hole diggers create clean, vertical holes. Augers are faster for rocky soil. Holes should be 3× the post width (12 inches for 4×4 posts).
Gravel base before concrete: Add 4-6 inches of gravel at the hole bottom before setting the post. This improves drainage and prevents rot by keeping the post end out of standing water.
Brace posts before concrete sets: Use temporary 2×4 braces in two directions to hold posts plumb while concrete cures. Check plumb with a level on adjacent sides. Don't remove braces for 24 hours.
Common Fence-Building Mistakes
Not checking property lines: Fences on your neighbor's property cause legal headaches. Get a survey or use your property deed and measure from known markers. When in doubt, set the fence 6-12 inches inside your property line.
Ignoring local codes: Most municipalities have fence height limits (4 feet in front yards, 6 feet in backyards), setback requirements, and permit rules. Check city/county codes before buying materials.
Setting posts too shallow: Shallow posts lean and eventually fail. Bury at least ⅓ of the total post length. A 6-foot fence needs 8-foot posts buried 2+ feet deep.
Building fence tight to the ground: Leave 2-4 inches between picket bottoms and the ground. This allows water drainage, prevents rot, and lets you mow without hitting the fence. Use a spacer board during installation.
Materials Needed
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Pro Tips
- Call 811 before digging — it's the law in most states. Free utility line marking.
- Post depth should be 1/3 of total post length (e.g., 2 ft deep for a 6 ft fence = 8 ft posts)
- Use concrete for corner and gate posts, gravel for line posts if you want easier future removal
- Place gates on level ground and avoid low spots where water pools
- For privacy fences taller than 6 ft, use 3 rails instead of 2 for rigidity
Frequently Asked Questions
Q: How much does fence material cost?
A: Pressure-treated wood: $15-25 per linear foot. Cedar: $25-40/ft. Vinyl: $30-50/ft. Chain link: $10-20/ft. Prices vary by height and style.
Q: Do I need to seal or stain a new fence?
A: Pressure-treated wood should wait 6-12 months before staining to let it dry. Cedar and redwood benefit from immediate sealing to prevent graying. Vinyl doesn't need sealing.
Q: Which side of the fence faces the neighbor?
A: Traditionally, the "good side" (smooth face) faces outward toward the neighbor as a courtesy. Some HOAs require this. Alternatively, use "good neighbor" fence designs with rails alternating sides so both sides look finished.
Q: How long does a wood fence last?
A: Pressure-treated pine: 15-20 years. Cedar: 20-25 years. Vinyl: 30+ years. Lifespan depends heavily on maintenance—sealed fences last 50% longer than unsealed.
Q: Can I build a fence on a slope?
A: Yes, using "stepped" or "racked" methods. Stepped follows terrain with level sections at different heights. Racked keeps pickets parallel to the slope for a continuous look. Racked is harder but looks better on gentle slopes.