Fence Post Calculator

Post count and spacing are the foundation of any fence project. Standard spacing for wood privacy fences is 8 feet on center; chain-link and lighter wire fences often run 10 feet between posts. Closer 6-foot spacing is stronger and recommended for tall fences, high-wind areas, and anywhere supporting heavy gates. The calculator adds one post for the end of the last section — a common mistake is forgetting that a 100-foot fence at 8-foot spacing needs 13 posts, not 12.

Post depth matters as much as post count. The standard rule is to bury one-third of the post's total length. For a 6-foot privacy fence, use 9-foot posts buried 3 feet deep. In regions with cold winters, posts must go below the frost line — typically 3–4 feet deep in the northern US — or frost heave will push them out of the ground and destroy the fence within a few seasons. Each post hole typically needs one 50-lb bag of dry concrete mix; use two bags for corner posts and gate posts that bear extra stress from swinging loads.

Gate posts carry significantly more load than line posts and should always be set in concrete regardless of what the line posts use. For heavy wood gates wider than 4 feet, use 4×6 posts instead of 4×4 posts, and set them at least 4 feet deep. Rails run horizontally between posts; use three rails (top, middle, bottom) for fences 6 feet or taller. Pickets and boards attach to rails and carry no structural load, but their width and spacing determine both the appearance and the total count. A 3.5-inch picket with no gap gives full privacy; a 5.5-inch board with a ½-inch gap creates the classic board-on-board look with airflow.