How many fence posts do I need?

Divide your total fence length by your post spacing (typically 6 or 8 feet on center) and add 1 for the starting post. For a 100-foot fence at 8-foot spacing: 100 ÷ 8 + 1 = 13.5 → 14 posts. Add 2 extra posts for each gate (one on each side). Use our calculator above with your exact measurements.

How much does it cost to build a fence per foot?

Wood privacy fence costs $15-30 per linear foot installed, including posts, pickets, rails, concrete, and labor. Vinyl fence runs $25-40 per foot. Chain link is the most economical at $12-20 per foot. DIY installation saves 40-50% on labor but requires a post hole digger or auger, level, and concrete mixing.

How deep should fence posts be set?

Fence posts should be buried at least 1/3 of their total height and extend below the local frost line. For a 6-foot fence, use 8-foot posts buried 2 feet deep (with 6 inches of gravel at the bottom for drainage). In frost-prone areas (northern US), posts must extend below the 24-42 inch frost line to prevent frost heave. Always check local building codes.

Fence Calculator — Panels, Posts & Rails

Calculate fence posts, panels, rails, pickets, and gates for your entire fence project — free and instant.

How to Use This Fence Calculator

Enter your total fence length (measure the entire perimeter). Choose fence height (4 ft decorative, 6 ft privacy, 8 ft security). Select material — wood privacy, shadowbox, vinyl, or chain link. Set post spacing (8 ft is standard for wood, 6 ft for heavy-wind areas, 10 ft for chain link). Add the number of gates. The calculator estimates posts, panels/sections, pickets, rails, and concrete bags for post footings.

How to Estimate Fence Materials: A Complete Guide

A fence defines your property, provides privacy, and keeps pets and kids safe. But fencing is one of those projects where the cost surprises people — what looks like "some wood and concrete" on paper turns into thousands of pounds of materials delivered on a flatbed. Here's how to calculate exactly what you need.

Posts: The Backbone of Your Fence

Fence posts are set in concrete every 6-10 feet, depending on material, wind load, and local code. Formula: (fence length ÷ post spacing) + 1 extra for the starting post + 2 per gate. A 100-foot fence at 8-foot spacing: 100 ÷ 8 + 1 = 13.5 → 14 posts. Plus 2 gates = 4 extra posts = 18 total.

Post sizing rules: for a 4-foot fence, use 4×4 posts (3.5" actual); for a 6-foot fence, 4×4 is standard but 6×6 corner and gate posts resist sagging better; for an 8-foot fence, use 6×6 posts throughout. Posts must be long enough to sit 2+ feet underground plus 6 inches of gravel at the bottom — for a 6-foot fence, buy 8-foot posts. In frost zones where holes must be 30-42 inches deep, upgrade to 10-foot posts.

Panels vs Pre-Built Sections vs Build-On-Site

Pre-built wood panels (6×8 ft, $50-80 each): The Home Depot special. Fast to install, but quality varies widely — check that the pickets are actually nailed, not just stapled. Most are 6 ft tall × 8 ft wide, designed for 8-foot post spacing.
Build-on-site wood: You buy posts, 2×4 rails, and individual pickets separately. Takes longer but produces a stronger, better-looking fence. Pickets come in standard widths (5.5" for a 6" dog-ear picket) with a slight gap (0.5-1") or tight-fit for full privacy.
Vinyl panels (6×6 or 6×8 ft, $100-180 each): Interlocking tongue-and-groove panels that slide into routed posts. No painting, no rot, no splinters — but they can crack in extreme cold and fade after 10-15 years in full sun. Replacement panels must match the exact brand and profile.
Chain link: Galvanized steel fabric in 50-foot rolls (4, 5, or 6 ft heights). Posts are 2-3/8" OD terminal posts and 1-7/8" OD line posts, set at 10-foot spacing. Top rail through post caps, tension wire at the bottom, tension bar through the fabric at each end. The most economical option by far — $12-20/ft installed.

Pickets and Rails: The Wood Fence Math

For a build-on-site wood privacy fence: Pickets needed = fence length (inches) ÷ (picket width + gap). Dog-ear pickets are 5.5" wide; with a 0.5" gap: 1,200 inches ÷ 6.0 = 200 pickets. Shadowbox fences use pickets alternating on both sides of the rail — double the count (400 pickets for the same 100-foot run).

Rails run horizontally between posts. A standard 3-rail design (top, middle, bottom) requires 3 rails per section. Number of rails = number of sections × 3. For a 100-foot fence at 8-foot spacing: 13 sections × 3 = 39 rails, each 8 feet long. Use 2×4 pressure-treated for the rails — they carry the full weight of the pickets and resist wind loads.

Gates: The Weakest Link

Gate posts take the most abuse on any fence. Every time a gate opens, the post resists the full cantilevered weight. Gate posts should be one size larger than your line posts (6×6 for a 4×4 fence), set in a deeper hole (30-36 inches minimum), and reinforced with an extra half-bag of concrete. Gate frames should be constructed with mortise-and-tenon or heavy-duty corner brackets — screws alone will pull out within a year. A double-drive gate (10-12 feet wide) needs a drop rod on the inactive leaf and an anti-sag cable or truss kit to prevent the gates from dragging.

Concrete for Post Footings

Each post hole needs 1-2 bags of 80lb concrete mix, depending on hole diameter and depth. A 10-inch diameter hole, 24 inches deep = 1.3 cubic feet of concrete = about 2.2 bags of 80lb mix per hole. For a 18-post fence: 18 × 2.2 = ~40 bags. Add a 6" layer of gravel at the bottom of each hole before setting the post — this prevents water from pooling around the post base and accelerates rot. For the exact concrete calculation by post count and hole size, use our Fence Post Concrete Calculator.

Fence Calculator