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Units

Composite Fence Calculator

Count composite fence sections, posts, pickets, rails, brackets and screws from the Trex Seclusions per-section list.

Units
Measure by
ft
corners

Where the fence turns.

Gates
4 ft gate
Composite fence details
ft
in

Follows the height. Go deeper if your frost line is lower.

Hole diameter: 12 in, three times the post width.

Enter a fence length, draw the line on the map, or add sides to see your materials.

How the composite fence calculator works

Composite privacy fences such as Trex Seclusions are built section by section: a post, two brackets top and bottom, a top rail, an aluminum bottom rail with covers, and a row of pickets. Trex publishes the parts for one 8 ft section, so the calculator counts your sections and multiplies.

Sections per stretch = stretch length ÷ 96 in, rounded up. Pickets = 19 per full section, in proportion for shorter ones, rounded up. Posts = sections + 1 on each stretch, with corners shared.

The Trex Seclusions installation guide lists the items used per 8 ft section of 6 ft fence: 1 post, 1 post cap, 4 brackets, 1 top rail, 19 pickets, 2 bottom rail covers and 1 aluminum bottom rail. Posts are set every 96 in on center. Each bracket takes four 1 5/8 in screws, and the first picket in a section is fixed with three more.

The calculator spaces the posts evenly along each straight stretch, never more than 96 in apart, so no section is left as a narrow stub. A section shorter than 96 in gets fewer pickets: 19 times its width over 96 in, rounded up.

A worked example

The calculator opens on a 150 ft fence, 6 ft high, with two corners and one 4 ft gate.

  • The gate leaves 146 ft to fence: two 50 ft sides and two 23 ft stretches beside the gate.
  • A 50 ft side (600 in) needs 7 sections, which works out to 85.7 in each. Each gets 19 × 85.7 ÷ 96 = 17 pickets, rounded up.
  • A 23 ft stretch (276 in) needs 3 sections of 92 in, with 19 pickets each (18.2 rounded up).
  • In all: 20 sections and 22 posts with 22 caps, 352 pickets, 20 top rails, 20 aluminum bottom rails, 40 bottom rail covers, 80 brackets and 380 screws (320 for brackets, 60 for first pickets).
  • Concrete: with 12 in holes, as Trex specifies, 42 in deep over 6 in of gravel, each post takes about 5.9 bags of 50 lb fast-setting mix, 131 bags in all.

How deep do the posts go?

Trex digs its holes 12 in wide and 30 in deep, and finishes posts 75 in above ground for a 6 ft fence. The calculator's default depth is 42 in, from Quikrete's rule of half the height above ground plus 6 in of gravel. Set the hole depth to 30 in and the same fence needs 88 bags, about 4 per post. In cold climates the frost line decides; dig below it whichever figure you start from. The fence post concrete calculator works out bags for any hole.

How far apart are composite fence posts?

For Trex Seclusions, 96 in on center. Family Handyman gives 8 ft as the standard for wood, composite and solid vinyl fences. The calculator never sets posts farther apart than 96 in unless you change the panel width.

Are the counts right for a 4 ft or 5 ft fence?

The per-section list in the Trex guide is for a 6 ft fence, and the guide gives no list for other heights. The calculator keeps the same per-section counts at any height and says so under the list, so confirm picket, rail and post sizes for a lower fence with your supplier.

What does it cost?

Composite is priced toward the top of the residential range. Fixr gives $22 to $40 per foot installed and $9 to $25 per foot for materials, while HomeAdvisor lists composite at $55 to $85 per foot. For a price on your own line, the fence cost calculator applies these ranges. To compare the same privacy screen in other materials, run it through the vinyl fence calculator or the privacy fence calculator, or the fence calculator for everything at once.