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Fence Calculator

Posts, rails and pickets for a fence run. The plus-one on posts is the part people miss: a fence with ten sections needs eleven posts, not ten.

Also called: fence post calculator, fencing materials.

Posts
20

20 posts at 2.4m spacing across 17 sections, plus 51 rails and 334 pickets. Concrete for the post holes comes to about 0.97 m³.

Sections
17
Rails
51
Pickets
334
Post-hole concrete (m³)
0.97
Post length including the buried part (m)
2.4
How this is calculated
Method and background

How this is calculated

Divide the length by the spacing and round up for the section count, then add one post because both ends need one. Rails multiply by sections and pickets divide the length by the picket width including its gap. Post holes are sized at roughly three times the post width and buried a third of the fence height, which is the conventional rule for a free-standing fence.

posts = sections + 1, because a fence needs a post at both ends
L
Fence length (metres)
s
Post spacing (metres)

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a forty metre run

Fence length (m)
40
Post spacing (m)
2.4
Fence height (m)
1.8
Rails per section
3
Picket width including gap (m)
0.12
Gates
1

Posts20

40 / 2.4 rounds to 17 sections, so 18 line posts plus 2 for the gate

Open this example

one section still needs two posts

Fence length (m)
2
Post spacing (m)
2.4
Fence height (m)
1.8
Rails per section
3
Picket width including gap (m)
0.12
Gates
0

Posts2

boundary: the plus-one that people miss

Open this example

Method and limits

What it assumes

  • Posts buried to a third of the above-ground height, which is the usual guidance.
  • A straight run. Corners and gates need their own posts.

What it deliberately does not model

  • Sloping ground needs stepped or raked sections and more material.
  • Gate posts carry more load and are usually larger than line posts.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why is it sections plus one?
Because posts sit between sections and at both ends. Ten panels have a post on each side of every panel, and the shared posts mean eleven rather than twenty.
How deep should posts go?
A third of the above-ground height is the common rule, so a 1.8 metre fence needs about 600mm buried, which makes the post 2.4 metres.