Fence Calculator

Calculate fence materials: posts, rails, and pickets. Enter fence length, post spacing, and picket dimensions to get a complete material list with waste.

ft

Total linear feet of the fence run.

ft

Distance between post centers. Standard: 8 ft. High-wind: 6 ft.

Horizontal rails per section. 2 for fences ≤4 ft, 3 for 5-8 ft.

ft

Length of rail boards you'll purchase. Common: 8, 10, 12, 16 ft.

in

Actual picket width. 1×4 = 3.5", 1×6 = 5.5". Use 0 for solid panel fences.

in

Gap between pickets. 0" = privacy, 2" = semi-privacy, 4" + = ranch/rail.

%

Extra for cuts, defects, mistakes. Default 10%.

How this calculator works

This fence calculator estimates materials in four steps:

  1. Posts: ceil(fence_length / post_spacing) + 1 (includes end post).
  2. Rails: sections × post_spacing × num_rails / rail_length (linear feet of rail boards needed).
  3. Pickets: for each section, ceil(post_spacing / ((picket_width + gap) / 12)) pickets. Multiply by sections.
  4. With waste: each material type gets the waste allowance applied independently.

For solid panel fences (no individual pickets), set picket width to 0 — the calculator skips picket counting.

Formula

posts              = ceil(fence_length / post_spacing) + 1
sections           = posts - 1
total_rail_ft      = sections × post_spacing × num_rails
rail_boards        = ceil(total_rail_ft / rail_length)
picket_plus_gap_ft = (picket_width + picket_gap) / 12
pickets_per_section = ceil(post_spacing / picket_plus_gap_ft)
total_pickets      = sections × pickets_per_section

with_waste = ceil(count × (1 + waste_pct / 100))

Example

For a 100 ft fence with 8 ft post spacing, 2 rails, 16 ft rail boards, 3.5" pickets with 2" gaps, 10% waste:

  • posts = ceil(100/8) + 1 = 14 posts
  • sections = 13
  • total_rail_ft = 13 × 8 × 2 = 208 linear ft
  • rail_boards = ceil(208/16) = 13 boards
  • picket_plus_gap = (3.5+2)/12 = 0.458 ft
  • pickets_per_section = ceil(8/0.458) = 18
  • total_pickets = 13 × 18 = 234 pickets
  • With waste: 16 posts, 15 rail boards, 258 pickets

Important assumptions

  • Standard post spacing: 8 ft for residential, 6 ft for high-wind areas or 6 ft fences.
  • Rails: 2 for fences ≤4 ft, 3 for fences 5-8 ft. 4 rails for 8 ft privacy fences.
  • Standard picket: 1×4 nominal = 3.5" actual. 1×6 = 5.5" actual.
  • Gap: 0" = privacy, 2" = semi-privacy, 4"+ = ranch/rail.
  • Concrete: each post needs 1-2 bags (60 lb). Use the Concrete Calculator for exact amounts.
  • Gate posts are heavier (4×6 or 6×6) — plan gate openings separately.

FAQ

How many fence posts do I need for 100 feet?
With 8 ft post spacing: ceil(100/8) + 1 = 14 posts. With 6 ft spacing: ceil(100/6) + 1 = 18 posts. Always add 1 for the end post.
How far apart should fence posts be?
8 ft on center is standard for residential fences. Use 6 ft spacing for 6 ft fences or high-wind areas. 4 ft spacing for very high wind or heavy fences.
How many pickets do I need for a 100 ft fence?
With 3.5" pickets and 2" gaps (0.458 ft spacing): ceil(8/0.458) = 18 per section × 13 sections = 234 pickets. With 10% waste: 258 pickets.
How much concrete do I need for fence posts?
Each post typically needs 1-2 bags of 60 lb concrete (depending on post size and hole depth). For a 100 ft fence with 14 posts: 14-28 bags. Use the Concrete Calculator for exact amounts.
Can I use this calculator for a solid panel fence?
Yes — set picket width to 0 and the calculator will skip picket counting, giving you only posts and rails. Panel fences use pre-built panels instead of individual pickets.