How to measure your fence line
Walk the line with a 100-foot tape or a measuring wheel and record each straight run separately — fence math is done per run, since posts land differently on a 40-foot run versus a 37-foot run. Add the runs together for total linear footage, then subtract gate openings and any sections where the house itself forms the boundary.
On slopes, measure along the ground (the fence follows the grade), not horizontally. If the slope is steep, consider stepping the fence — each section stays level and drops at the posts — which uses the same materials but looks far better than a fence that parallels a hill.
Posts: where fences fail
Every failed wood fence failed at the posts. Set them one-third of their length underground with a minimum of 24 inches — 30–36 inches for a 6-foot fence, and below the frost line (36–48 inches) in northern climates. Bell the bottom of the hole wider than the top so frost can't jack the post out.
Set posts in concrete, not dirt — but don't fill the hole to grade with concrete. Leave the top 4–6 inches for packed soil or gravel so water sheds away from the post instead of pooling against it. Slope the concrete crown away from the post. And use pressure-treated posts rated for ground contact (UC4A or better); standard treated lumber rots at the soil line in 5–7 years.
Material tips by style
- Privacy (6 ft): 5.5" pickets with a ¼" gap, three 2×4 rails per 8-foot section. Cedar resists rot naturally; pressure-treated pine costs 30–40% less.
- Picket (3–4 ft): 3.5" pickets spaced 2–2.5" apart, two rails per section. Spacing is the look — snap a chalk line and use a spacer block for consistency.
- Ranch rail (3-rail): 10-foot post spacing, 1×6 or 2×6 rails. The cheapest per foot and the fastest to build — no pickets at all.
- Gates: budget one extra post per gate (gate posts should be 6×6) plus hinges, latch, and a diagonal brace. Gates are a separate materials list — don't forget them.
- Fasteners: exterior screws or ring-shank nails only. Plan roughly 2 fasteners per picket per rail — a 150-foot privacy fence needs around 1,800 fasteners.
What affects fence cost
DIY materials for a 6-foot cedar privacy fence run $15–$30 per linear foot; pressure-treated pine $12–$22. Professionally installed, expect $30–$60 per linear foot, with gates adding $200–$500 each. Rocky soil, slopes, old fence removal, and permit fees all push quotes up.
The hidden cost is time: an experienced two-person crew builds 100–150 feet per day. A DIYer should plan a full weekend per 100 feet including post-setting cure time — don't hang pickets until concrete has set 24–48 hours.
Fence FAQs
How do I calculate fence materials?
Total linear feet ÷ post spacing + 1 = posts. Pickets: inches of fence ÷ (picket width + gap). Rails: 2–3 per section by fence height.
How many concrete bags per post?
One 60-lb bag per 4×4 post in a standard hole. Use two in soft soil, for 6×6 posts, or for gate posts.
How deep should fence posts be?
One-third of post length, minimum 24". For 6-foot fences use 30–36"; in frost zones, below the frost line (36–48").
How far apart should posts be?
8 feet on center is standard for wood privacy fence. Drop to 6 feet in high wind; ranch rail can span 10 feet.
Wood or vinyl fence?
Wood costs half as much upfront but needs staining every 3–5 years. Vinyl costs 2–3× more installed but is nearly maintenance-free for 20+ years.