Fence Calculator
Estimate posts, rails and pickets for a fence from the total length and post spacing.
How it works
sections = ceil(length ÷ spacing) · posts = sections + 1 · rails = sections × 2 · pickets = ceil(length × 12 ÷ picket width)
Dividing the run by the post spacing and rounding up gives the number of sections; posts are always one more than sections because both ends need one. Most fences use two rails per section (three for tall privacy fences), and picket count comes from the total length in inches divided by each picket’s width. This assumes a straight run without gate openings.
Worked example
A 100 ft fence at 8 ft spacing is 13 sections (100 ÷ 8 = 12.5, rounded up), so 14 posts and 26 rails. With 5.5 in pickets, 100 × 12 ÷ 5.5 ≈ 219 pickets.
Frequently asked questions
How far apart should fence posts be?
Six to eight feet is typical — 8 ft is common for panels and cost, 6 ft is sturdier and better in high wind or for heavy privacy panels. Never exceed the panel or rail span the material is rated for.
How deep do fence posts go?
A third of the post’s above-ground height, or at least 2 ft, and below the frost line in cold regions. A 6 ft fence usually means 8 ft posts set about 2 ft deep in concrete.
Which posts need concrete?
Corner, end and gate posts take the most stress and should always be concreted. Line posts can be set in tamped gravel for better drainage and easier future replacement, depending on soil and local practice.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.