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Fence Calculator

This fence calculator will be of great use to you if you want to build a fence on your own. Use it to plan your work by estimating the correct amount of fencing materials that you will need to complete your privacy fence project. Thanks to our fence estimator, you will know exactly what to buy and how much of it you need, which will answer a pressing question on your mind, how much does a fence cost?

How to use the fence calculator?

Fence calculator: fence parts.

Although our fence estimator may seem complicated at first, in reality, it is quite a simple tool. Read this short set of instructions to learn how to use it:

  1. Start by deciding how long your fence is going to be and how much space you want between posts. Typically, the post space is somewhere between 6 and 8 feet; or 2 and 5 meters, depending on your preference. Put the fence length and the space between posts in the first section of the fence calculator, and it will return both the number of posts you should buy and the number of sections defined by the number of posts, which is a value we will need later on.
  2. Put in the height of the fence in order to see the length of the posts you need to buy. That is important because at least ⅓ of every post should be buried in the ground and secured with concrete.
  3. Put in the number of horizontal rails per section of the fence. Two rails per section is the most common number, but it depends on the style of the fence. You will then get the total number of rails you need to buy. A rail is the same length as a section.
  4. Put the width of a single picket and the spacing between the pickets in the third section of the fence calculator in order to determine the total number of pickets.
  5. As every post needs to be secured so that your fence doesn’t fall over, you need to put the posts in holes filled with concrete. In order to calculate the volume of concrete needed to do that, input either:
    • The diameter of your post for cylindrical posts; or
    • The width and thickness of the post for cuboid posts.
Fence calculator: post measurements needed for concrete hole.

Equations used in the fence calculator

If you want to know how we calculate the amount of fencing materials you need, here is a list of the equations we used:

Number ofposts⏟round the result up=Fence lengthPost spacing+1
Number ofsections=Numberof posts−1
Post length=1.5×Fence height
Number ofrails=Railsper section×Numberof sections
Number ofpickets⏟round the result up=Fence lengthPicketwidth+Picketspacing

Formulas for concrete volume

The volume of the hole minus the volume of the part of the post that’s underground (buried post volume) results in the concrete volume for one post:

Concretevolume⏟for one post=Holevolume−Buriedpostvolume

Once you know the concrete volume for one post, multiply it by the number of posts, and you’ll get the total concrete volume for the entire fence.

To calculate the hole volume and the buried volume, we’ll need the post depth, which must be at least ⅓ of the post length:

Postdepth=Post length3

Now, let’s look at how to calculate the volumes for the two types of posts.

Cuboid post

For the cuboid post, the recommendation is to use a rectangular hole with three times the width and thickness of the post:


From the formulas above, we can obtain a final and easier-to-calculate equation for the concrete volume:

Concretevolume⏟for one post=8×Postwidth×Postthickness×Postdepth

Remember that you must multiply the concrete volume above by the number of posts to obtain the total concrete volume.

Cylindrical post

For the cylindrical post, we do something similar: use a hole whose diameter is three times the post diameter:


From the two formulas above, we can also obtain an easier equation for the concrete volume:

Concretevolume⏟for one post=2×𝜋×(Postdiameter)2×Postdepth

Again, multiply the concrete volume above by the number of posts to obtain the total concrete volume.

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