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Fence Calculator

Pickets, posts, rails, and concrete for a wood fence.

5.5" is a standard dog-ear picket

Posts, rails, pickets, and the concrete to set it all in — worked out from the length of fence you are actually building.

How it works

Posts are spaced along the run at a fixed interval (8 feet is the usual maximum), and you always need one more post than the number of sections. Rails are then two or three per section, and the picket count is the fence length divided by the picket width plus any gap between them. Each post hole needs concrete, which is calculated from the hole's diameter and depth, minus the volume the post itself takes up.

Example

A 100-foot fence at 8-foot post spacing needs 13 sections and 14 posts. With 5 1/2-inch pickets butted together, that is around 220 pickets.

Tips & common mistakes

  • Set the posts first and let the concrete cure before you hang anything on them. A rail attached to a post that is still green will pull it out of plumb, and you cannot fix it later.
  • Bury a third of the post. A 6-foot fence wants an 8-foot post with 2 feet in the ground — this is what the wind pushes against, and short-setting posts is why fences lean.
  • Put gravel in the bottom of the hole before the concrete so water can drain away from the end grain. A post sitting in a concrete cup full of water rots from the bottom up.
  • Call 811 before you dig. It is free, it is fast, and hitting a gas or fiber line is the most expensive mistake on this entire site.

Frequently asked questions

How far apart should fence posts be?

6 to 8 feet, with 8 feet being the common maximum for a standard wood fence. Closer spacing makes a noticeably stiffer fence and is worth it in windy spots.

How deep should fence posts be?

About one third of the post's total length, and below your local frost line. For a typical 6-foot fence that means digging roughly 2 feet.

How many bags of concrete per fence post?

Usually one to two 50-pound bags per hole for a standard 4×4 in a 10-inch hole, depending on depth. The calculator works it out from your actual hole size.