Privacy Fence Calculator

A wood privacy fence is built from three independently-counted material types — posts, rails, and pickets — and each one scales differently as fence length grows, which is why a simple "boards per foot" rule of thumb tends to be inaccurate on anything but a short run. Posts scale with the number of sections (length divided by post spacing, plus one), rails scale with sections multiplied by rails-per-section, and pickets scale with length divided by picket width. This calculator keeps those three counts separate rather than collapsing them into a single approximate board count, because ordering posts and rails short is a structural problem, not just a cosmetic one.\n\nThe picket-gap field exists because "privacy fence" is not always fully solid. A zero gap gives a true privacy fence with no sightlines through it, while a small gap (shadowbox or board-on-board style) still blocks direct view while improving airflow and reducing wind load on the fence — a real consideration in high-wind regions, since a solid fence acts like a sail and puts more lateral force on posts and footings than a fence with small gaps between boards.

The solid board privacy fence is a relatively recent form. Early North American fencing was agricultural and open by design, from split-rail and worm fences to the painted picket fences of colonial towns, which marked a boundary and kept livestock out without blocking sightlines. Solid vertical board fencing became a mass residential product only with the postwar suburban expansion of the late 1940s and 1950s, when small uniform lots put houses close enough together that visual screening between neighbors became the point of the fence, and when standardized dimensional lumber made stock pickets, 2x4 rails and 4x4 posts cheap and universally available. The 5.5-inch nominal 1x6 picket used in this calculator is a direct product of that lumber standardization. The durability of the form depended on wood preservation chemistry. Chromated copper arsenate, developed by the Indian chemist Sonti Kamesam in the 1930s, made softwood pine resistant to rot and insects and became the dominant preservative for ground-contact lumber through the second half of the twentieth century. The United States Environmental Protection Agency reached an agreement with manufacturers to end CCA-treated wood for most residential uses at the close of 2003, and the industry shifted to alkaline copper quaternary and copper azole formulations, which are more corrosive to fasteners and are the reason hot-dip galvanized or stainless steel screws and nails are now specified for fence construction. Naturally durable western red cedar and redwood remained the untreated alternatives, and shadowbox and board-on-board layouts developed as variants that keep most of the screening while letting wind pass through the fence line.