Fence Calculator

A wood fence is a repeating pattern of posts, rails, and pickets. The math for each is independent. Pickets: total pickets equals fence length in inches divided by picket width plus gap. For a 100 foot privacy fence with 5.5 inch pickets and no gap, that is (1200 / 5.5) = 219 pickets. For a picket fence with 3 inch gaps between 3.5 inch pickets, that is (1200 / 6.5) = 185 pickets.

Posts: total posts equals fence length divided by post spacing, plus one for the end. A 100 foot fence with 8 foot on-center posts is (100 / 8) + 1 = 13.5, rounded up to 14 posts. Gate openings need an extra post on each side of the gate.

Rails: total rail linear feet equals fence length times number of rails per section. A 6 foot privacy fence uses three rails (top, middle, bottom). A 4 foot picket fence uses two. For 100 feet with 3 rails, that is 300 linear feet of rail lumber.

Fence posts in Texas soil should be set 24 to 36 inches deep. The rule of thumb is one-third of the post above ground goes below ground: a 6 foot fence needs an 8 or 9 foot post set 2 to 3 feet deep. Corner and gate posts should go 6 inches deeper than intermediate posts.

Hole diameter should be 3 times the post width. A 4x4 post (3.5 inch) needs a 10 to 12 inch diameter hole. Fill the bottom 4 inches with gravel for drainage, set the post plumb, then fill with concrete to within 4 inches of grade. Slope the top of the concrete away from the post to shed water.

One 60 pound bag of fast-set concrete fills a 10 inch diameter hole to about 24 inches deep. Deeper holes and larger diameter (corners, gates) may need one and a half to two bags each.

Cedar is the traditional Texas fence wood. Western red cedar posts and pickets resist rot and insects naturally and weather to a silver gray over about 18 months. Cedar is the premium option and lasts 20 to 25 years with basic maintenance.

Pressure-treated pine is the budget option. Green treated 4x4 posts last 15 to 20 years. Treated 1x6 pickets last 12 to 15 years. The green tint fades to gray in about a year. Stain every 3 to 5 years to extend life significantly.

Metal T-post fences (chain link, welded wire) skip the concrete question entirely, but hot-dipped galvanized 2 3/8 inch line posts driven 3 feet into clay soil hold up better than concrete-set wood in areas where soil shrinks and swells.

Gates need special framing. A single 4 foot gate needs a diagonal brace from the bottom hinge corner to the top latch corner to prevent sag. Double gates (drive gates) need a drop rod that pins the inactive leaf to the ground and heavy-duty hinges rated for the gate weight.

Corners and ends need thicker posts. Standard construction uses 4x4 line posts and 4x6 or 6x6 corner posts. In high wind areas (most of West and Central Texas), use 6x6 corner posts regardless of the line post size.

Terminating at a building or existing fence requires a dedicated terminal post, not just nailing the last picket to the wall. This lets the fence expand and contract independently from the building.

Fence work is one of the most call-driven service categories in Texas. Storm damage, new construction, and property line disputes all trigger fast homeowner calls. Peak Local Leads builds and ranks fence-focused local sites for one contractor per market. Free week of calls, flat monthly after.