Fence Material Calculator

How this calculator works

A fence is a repeating structure: a post, a section of infill (a panel or a run of pickets on rails), another post, and so on. The calculator first subtracts your gate openings from the total length, then divides what remains into sections at your post spacing:

net length = total length − (gates × gate width)
sections   = net length ÷ post spacing        → rounded up
posts      = sections + 1 + (1 per gate)
panels     = net length ÷ panel width          → rounded up, then + waste
pickets    = net length (in) ÷ (picket width + gap) → rounded up, then + waste
rails      = sections × rails per section

The post formula bakes in one clearly stated assumption: every gate opening is framed by two posts, one of which is shared with the fence line, so each gate adds exactly one post beyond the usual sections + 1. Concrete is figured per post hole as a cylinder (footing diameter × depth) divided by the cured yield of your bag size. The post's own displacement isn't subtracted, which leaves a small built-in margin — useful, since holes are rarely drilled to exact size.

In picket mode the calculator also counts screws (two per picket per rail) and boxes them up, and in both modes it reports the stain or paint coverage area so you can size that purchase separately.

Worked example: 100 ft of 6 ft privacy fence

Take the calculator's defaults: 100 ft of fence, 6 ft tall preassembled panels 8 ft wide, posts 8 ft on center, one 4 ft gate, and 10% waste:

• Net length: 100 − (1 × 4) = 96 ft of fence line.
• Sections: 96 ÷ 8 = 12 sections.
• Posts: 12 + 1 = 13 line posts, plus 1 extra for the gate = 14 posts.
• Panels: 96 ÷ 8 = 12 panels; with 10% waste, 13.2 → buy 14.
• Concrete:each 10 in × 24 in hole holds about 1.09 cu ft; 14 holes ≈ 15.3 cu ft; at 0.375 cu ft per 50 lb bag that's 40.7 → 41 bags.
• Stain area: 96 ft × 6 ft × 2 sides = 1,152 sq ft of surface to coat.

Every one of those numbers appears in the results panel, along with the assumption that produced it — change the assumption and the number updates.

How to measure for a fence

• Walk the line with a long tape or measuring wheel. Measure each straight run separately and add them up; corners are where small errors accumulate.
• Include gate openings in the total. The calculator subtracts them for you — measuring around them by hand is a common source of double-counting.
• Mark corners and gates with stakes before measuring so the tape follows the actual fence path, not the shortcut across the yard.
• Note slopes. Steady grades work fine with either construction type, but panels on a steep slope must either step down (leaving triangular gaps) or be special-ordered. Picket-built fences can rack to follow the ground.
• Confirm the property line.A survey or the recorded plat beats guessing from the old fence — neighbors' fences are not reliable markers.

Our guide How to Measure a Home Project covers tools and technique in more detail.

Buying fence materials

• Match panel width to post spacing. Stock panels are 8 ft (some 6 ft); if your spacing differs, every section needs a trimmed panel. Set post spacing to the panel width unless the layout forces otherwise.
• Posts drive the schedule. Use ground-contact-rated pressure-treated 4x4s (or steel posts with brackets), and buy them long enough: fence height plus burial depth. A 6 ft fence with 24 in deep holes needs 8 ft posts.
• Upsize gate posts. A sagging gate is usually a post problem. Many builders use 6x6 posts and a larger footing at gates, especially for openings over 4 ft.
• Fasteners must match treated lumber. Use hot-dip galvanized, polymer-coated, or stainless screws rated for pressure-treated wood — bright screws corrode quickly against it.
• Price both construction types. Panels cost more per foot of material but far less labor; pickets are cheaper per foot and handle slopes and custom heights better. Enter prices for each mode in the calculator to compare totals — our material cost guide shows how to collect prices efficiently.

Common estimating mistakes

• Forgetting that posts outnumber sections by one. Twelve sections need thirteen posts, not twelve — and each gate adds another. Running one post short stops the job mid-dig.
• Estimating pickets by nominal width.A "6-inch" picket is 5-1/2 inches wide. Using 6 inches in the math shorts you roughly 9% of your pickets before waste.
• Ignoring the gap in spaced-picket styles. A 2-1/2 inch gap with 5-1/2 inch pickets cuts the picket count by nearly a third compared to a privacy layout.
• Underestimating concrete. Post holes are bigger than they look: a 10 in × 24 in hole swallows most of three 50 lb bags. Buying concrete twice wastes a trip; unopened bags can go back.
• Setting posts before utilities are marked or lines confirmed. Both mistakes are expensive in the worst way — one is dangerous, the other can mean tearing the fence out.

Limitations

This tool models a straight-run fence built from equal sections. It doesn't optimize post layout across multiple runs and corners (each corner effectively adds a post), doesn't design for wind load or unusual soils, and treats the gate as an allowance rather than a framed structure with its own parts list. Concrete per hole is a simple cylinder — rocky or sandy ground changes real-world usage. Stain coverage is reported as area only; divide by your product's coverage rate to get gallons. Treat the output as a shopping estimate to verify against your layout drawing, not a construction plan.