Fence Calculator
Enter the length of the fence and how far apart the posts go. This counts the posts, the rails, the pickets and the concrete that holds it all up.
How the math works
Sections = fence length divided by the post spacing, rounded up. Posts = sections + 1, because a straight run needs a post at both ends. Hole depth = one third of the fence height, and never less than two feet. Concrete per hole = the volume of the hole minus the part of the post sitting in it.
Common questions
- How many fence posts do I need for 100 feet?
- Fourteen at eight foot spacing: 100 divided by 8 is 12.5 sections, rounded up to 13, and a straight run always needs one more post than sections.
- How deep should a fence post go?
- A third of the post above ground, with a two foot minimum. A six foot fence needs a two foot hole, an eight foot fence needs closer to three. Go below the frost line in cold climates, or the posts lift every winter.
- How many bags of concrete per fence post?
- One to two 80 pound bags for a 4x4 in a 10 inch hole two feet deep. A 6x6 in a 12 inch hole takes three or four.
- How far apart should fence posts be?
- Eight feet is standard and matches stock rail lengths. Six feet on a windy site or with heavy prefabricated panels. Ten feet only for wire or open rail fencing.
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