Fence Calculator
Calculate how many fence posts, rails, and panels you need for any fence project.
How to use this tool
- Enter the total fence length in linear feet.
- Set your post spacing (typically 8 ft) and rails per section (typically 3).
- The calculator returns the number of posts, rails, and panels/sections.
Calculate all the materials you need before building a fence.
Formula
Panels = ⌈ total length (ft) ÷ post spacing (ft) ⌉
Posts = panels + 1
Rails = panels × rails per section
How it works
This calculator determines the number of fence sections (panels), posts, and rails for a straight fence run. The number of panels is found by dividing the total fence length by the post spacing and rounding up, which ensures the full length is covered even if the last section is shorter than a full bay. Posts always number one more than panels because a post is required at each end as well as between sections. Rails are simply the number of panels multiplied by the rails used per section. The tool assumes a straight, single-run fence with no gates; gates and corners would each require an additional two posts.
Worked example
Worked example
- Panels = ⌈100 ft ÷ 8 ft⌉ = ⌈12.5⌉ = 13 panels.
- Posts = 13 + 1 = 14 posts.
- Rails = 13 × 3 rails per section = 39 rails.
A 100 ft fence with 8 ft post spacing and 3 rails per section needs 14 posts, 39 rails, and 13 panels.
Key terms
- Panel / section
- The infill area of fencing between two consecutive posts; also the unit used when buying pre-made fence panels.
- Post spacing
- The on-center distance between fence posts, typically 6–8 feet for wood or vinyl fencing.
- Rail
- A horizontal structural member running between posts that supports the fence boards or pickets; most privacy fences use 2–3 rails per section.
- Terminal post
- An end or corner post that terminates a fence run; the '+1' in the posts formula accounts for the second terminal post at the far end.
Frequently asked questions
- How far apart should fence posts be?
- Most fence posts are spaced 6 to 8 feet apart. Pre-made fence panels often dictate 6 or 8 ft spacing. Corner and gate posts are always additional.
- How many rails does a 6-foot fence need?
- A standard 6-foot privacy fence typically uses 3 horizontal rails (top, middle, and bottom) between posts.