Enter the length of the fence, the post spacing, the number of gates and the picket size. The calculator gives the posts, rails and pickets for a straight run of wood fence.
Fence formulas
Fence run = total length − gates × gate width Sections = run ÷ post spacing, rounded up Posts = sections + 1 + one extra post per gate Rails = sections × rails per section Pickets = run (in) ÷ (picket width + gap), rounded up
Worked example: 100 ft with one 4 ft gate
- Run without the gate: 96 ft.
- Sections at 8 ft: 12; posts: 12 + 1 + 1 = 14.
- Rails: 12 × 2 = 24.
- Pickets: 96 × 12 ÷ (5.5 + 0.5) = 192.
Post spacing
Wood fences are commonly built with posts 6 to 8 ft apart; this is a common practice rather than a rule from one source. Closer spacing makes a stiffer fence and is usual for tall privacy fences in windy areas. Your fence supplier, HOA or local code may set a maximum, so check before you dig. Each corner and end needs a post, so add one post for every extra corner on an L- or U-shaped fence.
Also plan for
- Concrete for the posts: use the post hole concrete calculator.
- Hardware: rail brackets or screws, gate hinges and a latch.
- Stain or sealer: the deck stain calculator works for fences too, using both sides of the fence.
Questions
How many pickets for 100 ft of fence?
About 200 with 5.5 in pickets and 1/2 in gaps, or 219 for a privacy fence with no gaps.
How many posts for a 100 ft fence?
14 posts at 8 ft spacing with no gates.
Do I need 3 rails?
Fences taller than about 5 ft often use 3 rails to stop the pickets bowing.
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: Foot and inch definitions.