Calculate fence post spacing, length, thickness or number of posts from three inputs in feet, yards, meters, inches, cm or mm.

Fence Post Distance Calculator

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Fence Post Spacing Formula

The following formula is used to calculate the Fence Post Spacing (clear distance between adjacent posts) for a straight fence run when the fence length includes the posts and the gaps between them.

FPD = (L*12 - FP*T)/(FP - 1)
  • Where FPD is the Fence Post Spacing (in)
  • L is the length of the fence (ft) 
  • FP is the number of fence posts 
  • T is the thickness of one fence post (in) 

To calculate fence post spacing, convert the fence length to inches (multiply by 12), subtract the total thickness of all posts (FP × T), then divide by the number of spaces between posts (FP − 1).

How to Calculate Fence Post Spacing?

The following example problems outline how to calculate Fence Post Spacing.

Example Problem #1

  1. First, determine the length of the fence (ft).
    • The length of the fence (ft) is calculated to be : 60.
  2. Next, determine the number of fence posts.
    • The number of fence posts is measured to be: 45.
  3. Next, determine the thickness of the fence post (in).
    • The thickness of the fence post (in) is found to be: 5.
  4. Finally, calculate the Fence Post Spacing using the formula above: 

FPD = (L*12 – FP*T)/(FP – 1)

The values given above are inserted into the equation below and the solution is calculated:

FPD = (60*12 – 45*5)/(45 – 1) = 11.25 (in)


Example Problem #2

The variables needed for this problem are provided below:

length of the fence (ft) = 100

number of fence posts = 50

thickness of the fence post (in) = 3

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

FPD = (L*12 – FP*T)/(FP – 1) = (in)