Enter the length of the fence, the number of fence posts, and the thickness (width) of each fence post into the Fence Post Spacing Calculator. The calculator will evaluate and display the Fence Post Spacing (the clear distance between adjacent posts).

Fence Post Distance Calculator

Enter any 3 values to calculate the missing variable

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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)