A fence material estimate starts with the linear footage and ends with a surprisingly long list: posts, rails, pickets or panels, concrete, gravel, hardware, fasteners, gate kits, post caps, and stain or paint. Missing any one of these items stops the job until someone makes another trip to the lumber yard.
The most expensive mistakes in fencing are underground — setting posts too shallow (they lean within 2 years), not accounting for frost line depth (freeze-thaw heaves the posts), and under-sizing gate posts (gates sag under their own weight). This guide covers the structural decisions first, then the material lists for six common fence types.
Post Depth and Frost Line Rules
Post depth is the single most important structural decision in a fence. The rules:
Minimum Depth: 1/3 of Total Post Length
A 6-foot fence uses 8-foot posts with 2 feet in the ground. This is the absolute minimum for stability. For fences over 6 feet tall or in areas with high wind exposure, use the 1/3 rule: one-third of the total post length underground. An 8-foot privacy fence needs posts buried at least 2 feet 8 inches, so use 11-foot or 12-foot posts.
Below the Frost Line
In cold climates, the bottom of the concrete footing must be below the local frost line. If the frost line is 36 inches (common in the upper Midwest) and you set a post at 24 inches, freeze-thaw cycles will heave the concrete and post out of the ground over a few winters. The post holes must be deeper than the frost line regardless of the 1/3 rule.
Approximate frost line depths by region:
- Southern US (FL, TX coast, AZ low desert): 0–6 inches
- Mid-Atlantic and Southeast: 12–18 inches
- Central US (KS, MO, KY): 24–30 inches
- Northern US (MN, WI, MI, New England): 36–48 inches
- Alaska, northern mountain states: 48–72 inches
Hole Diameter
Post holes should be 3 times the post width. A 4×4 post (actual 3.5") gets a 10–12 inch diameter hole. A 6×6 post (actual 5.5") gets a 16–18 inch diameter hole. Wider holes provide more concrete around the post for lateral stability.
Call 811 before digging. Buried utility lines (gas, electric, water, cable, fiber) can be as shallow as 12 inches. A post-hole digger or auger hitting a gas line is a life-threatening emergency. Utility locates are free and legally required in all 50 states. Schedule at least 3 business days before your dig date.
Fence Material Calculator
Calculate posts, rails, pickets, concrete, and hardware for wood privacy, shadowbox, split rail, chain link, vinyl, and metal panel fences. Frost line depth integration and gate sizing.
Concrete Per Post Hole
Each post needs concrete to lock it in place. The volume of concrete per hole depends on hole diameter and depth:
Quick Calculation
Volume (cubic feet) = π × (hole radius in feet)² × depth in feet. For a 10-inch diameter hole at 24 inches deep: π × (5/12)² × 2 = 0.87 cu ft. A standard 80-lb bag of premixed concrete yields about 0.6 cu ft. So each post hole needs roughly 1.5 bags.
Common Post Hole Sizes
| Hole Size | Depth | Volume (cu ft) | 80-lb Bags |
|---|---|---|---|
| 10" diameter | 24" | 0.87 | 1.5 bags |
| 10" diameter | 36" | 1.31 | 2.2 bags |
| 12" diameter | 24" | 1.26 | 2.1 bags |
| 12" diameter | 36" | 1.88 | 3.1 bags |
| 12" diameter | 48" | 2.51 | 4.2 bags |
Setting Method
The fastest method is dry-pour: set the post plumb in the hole, pour dry premixed concrete around it, then add water. The concrete absorbs ground moisture and cures over 24–48 hours. This is adequate for standard fence posts. For gate posts and corner/end posts that bear more load, mix the concrete wet in a wheelbarrow and pour it around the post for a denser, stronger footing.
Gravel Base
Put 3–4 inches of gravel at the bottom of every post hole before the post and concrete. The gravel provides drainage so water does not pool at the base of the post. Standing water at the post base accelerates rot, even on pressure-treated wood. This gravel depth is in addition to the concrete depth — so a 24-inch concrete depth needs a 28-inch hole.
Bags per hole = (π × r² × depth) ÷ 0.6
Where r = hole radius in feet, depth in feet, 0.6 = cu ft per 80-lb bag.
Example: 12" hole, 36" deep = (3.14 × 0.5² × 3) ÷ 0.6 = 3.9 bags. Round up to 4.
Post Spacing and Layout
Post spacing depends on fence type and material:
Standard Spacing
- Privacy fence (wood): 6 feet on center for standard pickets and 2×4 rails. Some builders use 8 feet with heavier rails (2×6 or steel) but 6 feet is more rigid and handles wind load better.
- Picket fence: 6–8 feet on center. Lighter loads allow wider spacing.
- Split rail: 8–10 feet on center. Rail lengths determine spacing (10-ft rails are standard).
- Chain link: 10 feet on center for residential, with line posts. Terminal posts (corners, ends, gate posts) are heavier gauge and set in larger concrete footings.
- Vinyl/PVC: Per manufacturer — typically 6–8 feet to match panel width.
Corner and End Posts
Corner posts, end posts, and gate posts bear more lateral force than line posts. Upgrade these to 6×6 (for 4×4 line post fences) or use steel reinforcement. Corner posts resist the pulling force of two fence sections meeting at an angle. Gate posts resist the constant leverage force of the gate swinging open and closed.
Counting Posts
Number of posts = (total fence length ÷ post spacing) + 1. A 100-foot fence at 6-foot spacing needs 100 ÷ 6 + 1 = 17.7, rounded up to 18 posts. Do not forget to count the first and last post. Add extra posts at every corner, gate location, and direction change.
Lay out the entire fence line with stakes and string before digging. Measure post locations from one end and mark each with a stake. This reveals problems before you start digging — a post landing on a rock, too close to a tree root, or where the ground drops steeply. Moving a stake is free; moving a hole full of concrete is not.
Gate Post Sizing and Reinforcement
Gate posts are the most common point of failure in residential fences. A gate exerts continuous leverage on its hinge post every time it opens and closes. The latch post must resist the gate's weight pulling it out of plumb. Under-sized gate posts start leaning within a year.
Gate Post Rules
- Single walk gate (3–4 ft wide): 4×6 or 6×6 posts, set 6 inches deeper than line posts, with 50% more concrete.
- Double drive gate (8–12 ft wide): 6×6 posts minimum. Steel posts (2-3/8" or 4" schedule 40 pipe) are better for drive gates because they do not twist or warp. Set 12 inches deeper than line posts.
- Heavy gates (solid wood, decorative iron): Steel posts set in concrete with a minimum 12-inch diameter hole at 48 inches deep, regardless of frost line.
Gate Hardware
Use heavy-duty strap hinges rated for the gate weight, not lightweight T-hinges. A 4-foot wide privacy gate can weigh 60–80 lbs. Three hinges are standard for gates over 5 feet tall. Self-closing hinges with adjustable tension are available for gates that must close automatically (pool fences, childproofing).
Gate latches should be self-latching for pool fences (code requirement in most jurisdictions) and gravity-latching for all other applications. Spring-loaded latches wear out faster than gravity latches.
Pool fence gates MUST be self-closing and self-latching per the International Residential Code (IRC R326) and local pool barrier codes. The latch must be on the pool side of the gate and at least 54 inches above grade. Non-compliant pool gates fail inspection and create a drowning hazard.
Material Lists by Fence Type
Per 100 linear feet of fence at standard heights. Adjust quantities proportionally for your actual length.
6-ft Privacy Fence (Wood)
- Posts: 18 × 4×4×8 ft pressure-treated ($12–$18 each)
- Rails: 34 × 2×4×8 ft (2 per bay × 17 bays) ($5–$8 each)
- Pickets: 200 × 1×6×6 ft ($3–$5 each) or 17 pre-built panels ($50–$90 each)
- Concrete: 36 bags 80-lb (2 per post)
- Post caps: 18 ($2–$8 each)
- Screws: 10 lbs exterior-grade 2.5" or 3" ($8–$12/lb)
- Material cost: $1,200–$2,200
4-ft Picket Fence (Wood)
- Posts: 14 × 4×4×6 ft ($10–$14 each)
- Rails: 26 × 2×4×8 ft ($5–$8 each)
- Pickets: 300 × 1×4×4 ft dog-ear ($1.50–$3 each)
- Concrete: 28 bags 80-lb
- Screws: 8 lbs
- Material cost: $800–$1,400
Chain Link (4 ft Residential)
- Terminal posts: 2 (ends) + corners + gates × 2-3/8" galvanized
- Line posts: 10 × 1-5/8" galvanized (10 ft spacing)
- Top rail: 100 ft × 1-3/8" galvanized
- Chain link fabric: 100 ft × 4 ft roll, 11 or 11.5 gauge
- Tension wire, tension bands, brace bands, ties, rail caps
- Material cost: $600–$1,000
Pre-built fence panels (sold in 6- or 8-foot sections) save significant labor but cost 10–20% more than building from individual pickets and rails. Panels are also limited to standard heights and styles. Board-on-board and shadowbox patterns usually need to be built on-site from individual boards.
Wood Treatment, Stain, and Maintenance
Untreated wood fences rot. Pressure-treated wood lasts longer but still benefits from stain or sealant. The treatment decisions you make at installation determine whether the fence lasts 8 years or 25.
Pressure-Treated Lumber
All ground-contact posts should be pressure-treated to UC4A or UC4B ground-contact rating. Standard above-ground treated lumber (UC3B) is adequate for rails and pickets. The treatment prevents rot and insect damage. Do not substitute untreated lumber for posts — even cedar or redwood heartwood rots at the soil line within 5–8 years without treatment.
Stain vs Paint
- Stain (penetrating): Soaks into wood grain. Does not peel or crack. Fades gradually and can be re-stained without stripping. Best for cedar, redwood, and situations where low maintenance matters. Semi-transparent stain shows grain; solid stain hides grain like paint but does not peel.
- Paint (film-forming): Sits on the surface. Provides the most uniform color. Cracks and peels over time, requiring scraping and repainting every 3–7 years. Looks best initially but highest long-term maintenance.
- Clear sealant: UV protection and water repellency without color. Must be reapplied every 1–2 years. Good for preserving natural wood color on cedar or redwood.
Coverage Rates
Stain: 150–300 sq ft per gallon depending on wood porosity and product. New pressure-treated wood soaks up more stain. A 100-foot privacy fence (6 ft tall) has about 1,200 sq ft of surface area (both sides = 2,400 sq ft if staining both). That is 8–16 gallons for one side.
Wait 2–4 weeks after installation before staining new pressure-treated wood. The treatment chemicals need to dry for stain to absorb properly. Test with a water drop — if water beads on the surface, the wood is not ready for stain.
Stain both sides and all end-cuts of fence boards before installation. End grain (cut ends) absorbs moisture fastest and is the primary entry point for rot. A quick dip of each board end in stain before nailing adds years of life at minimal cost.
Frequently Asked Questions
Minimum one-third of total post length underground (e.g., 2 feet deep for a 6-foot exposed fence using 8-foot posts). In cold climates, the bottom of the concrete must be below the local frost line (36–48 inches in the northern US). Use whichever depth is greater.
For a standard 4×4 post in a 10-inch diameter hole at 24 inches deep: 1.5 bags of 80-lb premixed concrete. At 36 inches deep: about 2.5 bags. For 6×6 gate posts in 12-inch holes: 3–4 bags each. Always buy a few extra bags — the cost is minimal compared to a return trip.
6 feet on center for wood privacy fences. 8 feet for picket fences and some panel systems. 10 feet for chain link and split rail. Post spacing is measured from center to center, not from edge to edge. Your rail or panel length must match the spacing.
Most jurisdictions require a permit for fences over 6 feet tall. Many require permits for any fence in a front yard or within a setback. Some HOAs have additional restrictions on height, style, and material. Check with your local building department and HOA (if applicable) before ordering materials.
Pressure-treated wood fences last 15–20 years with proper installation (posts below frost line, concrete footings, gravel drainage). Without stain or sealant, the wood grays and may check (crack along the grain) but the treatment prevents structural rot. Cedar fences last 15–25 years. Untreated pine lasts 5–8 years.
4×4 posts are standard for fences up to 6 feet tall in low-wind areas. 6×6 posts are recommended for fences over 6 feet, high-wind locations, all gate posts, corner posts, and end posts. 6×6 posts provide significantly more rigidity and resist the leverage force of tall panels in wind.
Yes, using either the step method (panels remain level, stepping up at each post — leaves triangular gaps at the bottom) or the rack method (panels follow the slope — requires picket-built sections, not pre-built panels). The step method is simpler but the gaps may need fill boards or gravel boards at the bottom for privacy.