Free online fence calculator

How to use

1. Enter total fence length and height in feet.
2. Set your post spacing (8 ft is standard).
3. Enter the number of gates.
4. Choose your fence type.
5. Read posts, concrete, rails, pickets or rolls, and gate posts.

Formulas

postsNeeded    = ceil(fenceLength / postSpacing) + 1
gatePostsNeeded= gateCount × 2
concreteBags   = ceil((postsNeeded + gatePostsNeeded) × 0.5)

Privacy / Picket:
  railsPerSpan = ceil(fenceHeight / 2)
  spans        = ceil(fenceLength / postSpacing)
  rails        = ceil(spans × railsPerSpan × wasteMultiplier)
  pickets      = ceil(fenceLength × 3 × wasteMultiplier)

Split-rail:
  railsPerSpan = 2 (height ≤ 3 ft) or 3 (taller)
  rails        = ceil(spans × railsPerSpan × wasteMultiplier)

Chain-link:
  rolls = ceil(fenceLength × wasteMultiplier / 50)

Worked example

150-ft privacy fence, 6-ft height, 8-ft post spacing, 1 gate, 10% waste:

postsNeeded    = ceil(150/8) + 1 = 19 + 1 = 20
gatePostsNeeded= 1 × 2 = 2
concreteBags   = ceil(22 × 0.5) = 11 bags

railsPerSpan   = ceil(6/2) = 3
spans          = ceil(150/8) = 19
rails          = ceil(19 × 3 × 1.10) = 63 rails

pickets        = ceil(150 × 3 × 1.10) = 495 pickets

Notes

• Set posts 1/3 to 1/2 their total length into the ground — a 9-ft post gives 6 ft above grade.
• In frost-heave regions, bury posts below the frost line (typically 42–48 in in the northern US).
• Gate posts need to be at least one size larger than line posts to handle the swing load.