Fence Post Spacing Calculator

Divide your total fence length by the post spacing (e.g., 8 ft), round up to get the number of sections, then add 1. Formula: posts = ceil(length ÷ spacing) + 1. For a 100-ft fence at 8-ft spacing: ceil(100 ÷ 8) + 1 = 13 + 1 = 14 posts. Add gate post pairs on top of this.

8 feet on center is the industry standard for wood and vinyl fences because it matches standard lumber lengths (8-ft and 16-ft boards produce zero waste). Chain link uses 10-ft spacing. Board-on-board and horizontal fences perform better at 6-ft spacing due to increased panel weight.

Always divide your total run into equal sections. If your 47-ft run at 8-ft spacing gives 5.875 sections, round up to 6 sections, then divide 47 ÷ 6 = 7.83 ft per section — and set all 7 sections at 7.83 ft. This avoids a short awkward gap at one end. The calculator shows this equal-division spacing in the results.

The rule of thumb is one-third of the total post length underground. For a 6-ft fence using 8-ft posts, set the post 2 ft deep. In cold climates, posts must go at least 6 inches below the frost line regardless of the one-third rule. Poor soil or clay requires deeper setting and more concrete.

Concrete is recommended for all posts. End posts, corner posts, and gate posts should always be set in concrete. For line posts in firm, well-drained soil, some contractors use compacted gravel instead of concrete, but concrete provides more reliable long-term stability. The standard estimate is 1 bag of 60-lb concrete per post at 8-inch diameter, 24–36 inches deep.