Please note: For your convenience, this calculation has been rounded up slightly.
Important reminder: Every effort has been made to ensure the accuracy of this calculation. But before purchasing materials for any project, please check amounts with your suppliers or contractors.
You can compute how much material you'll need for a picket fence like that shown in the article Adding a Perimeter Fence. This estimator calculates the horizontal distance from the right edge of a picket to the right edge of the next picket. It is fairly common for pickets to be "self-spaced" -- for the space between to be the same as the picket width.
There are three major components of a picket fence: vertical posts, horizontal rails, and vertical pickets. The posts are 4x4s, set every 6 feet. The post holes may be filled with concrete, or with well-tamped soil. Two 2x4 horizontal rails -- one about 6 inches above the ground and the other about 6 inches from the tops of the pickets -- run between the posts. (Because of the thickness of the posts, the rails must be cut to fit between the posts.) Pickets may be 1x3 or 1x4.
A few tips: To avoid rot, use pressure-treated lumber or the dark heartwood of cedar or redwood.
To self-space 1x3s, the edge-to-edge spacing is 5.5". To self-space 1x4s, the edge-to-edge spacing is 7". (If you plan to put pickets on both sides of the fence, double the figure for number of pickets.)