How Much Cement For Fence Post

How Much Cement For Fence Post?

It is important to use enough cement for our fence post. Using insufficient cement will make your fence post unstable, and it won’t last long.

After knowing how deep your fence post should be, all you have to do is determine how much cement is needed for a fence post. But how do you determine that?

We explained how to calculate the amount of cement needed for a fence post, all the conditions that matter, and how to install a fence post in concrete.

Should I Use Concrete for Fence Posts?

Whether it’s DIY or professional, a sturdy fence post Is essential no matter what type of fence you are setting up. There are various options for setting up a fence post they include dirt, crushed rocks, travels, or concrete.

But out of all these options, concrete is the most solid support for your fence post. It is the perfect setting for loose soil (sandy soil), but we recommend that you use pre-mixed concrete instead of a dry one for more sturdiness.

But while concrete may be the best material to secure your fence pose, it does not have a good drainage system like travels or dirt. This means your concrete will absorb water which will lead to rot.

How Much Cement Do You Need for your Fence Post Project?

It will be a pain to discover that you have insufficient cement halfway into installing your fence post, and you also don’t want excess cement lying around in your yard; that is why it is essential to have just the right amount of cement.

The amount of concrete being used depends on the size of your home. A bigger hole will require more cement than a smaller hole. Your hole should be three times the diameter of your fence post.

For a regular-sized hole, one bag of cement should be enough, but a big hole will take more than that amount of concrete.

What Kind of Concrete Gives Me the Best Value?

There are different types of concrete, all of which can be used for different purposes, and the kind of concrete that will give you the best value depends on the concrete type. The first type of concrete is the normal strength concrete.

Normal strength concrete mixes the basic ingredients in a ratio of 1:2:4. This concrete is not great at withstanding stress and is used mainly for pavement or buildings that don’t need tensile strength.

Ordinary concrete mixes in the same ratio as normal concrete; it also has the same problem as normal concrete and takes 30 to 90 minutes to set.

Reinforced concrete is becoming popular in modern-day construction. The strength of this concrete is boosted by inserting cables, iron rods, or wires inside the concrete before It sets. This concrete is resistant to stress and will last a long time when used.

Other types of concrete include prestressed concrete, volumetric concrete, ready-mix concrete, and lightweight concrete.

While reinforced concrete is the best type for fence posts, it is expensive and requires a lot of time and additional materials. A better choice is the quikrete concrete mix. It is easy to use and stress-resistant.

How Much Concrete Per Fence Post

The amount of concrete used for a fence post depends on the type of fence, size of the fence post, and soil type; without considering these factors, you will need 1 to 4 bags of concrete per fence post.

As we have mentioned earlier, to determine the size of your fence post hole, it needs to be three times the diameter of your post, and the hole needs to be ⅓” of the height of your post.

A good example can be shown when you have a fence post 7 feet high. Your post should be 3 to 4 feet underground.

And if the diameter of our post is 5 inches, the width of your hole will be three times the diameter of your fence post, which is 15 inches. The amount of concrete that can fill this hole is six bags of 85lbs concrete.

How Do You Calculate Concrete for Fence Posts?

Basic math is needed to calculate the amount of concrete needed for a fence post. You’ll need the following details to calculate the amount of concrete needed for a fence post.

  1. The number of posts to be installed
  2. The size of the post
  3. Height and diameter of the post.

The following detailed steps should guide you to determine the amount of concrete needed for a fence post.

Step 1:

The first step is to calculate the post hole’s volume, which can be done by calculating the hole’s radius. This can be done by multiplying the radius of your post by 3.

The volume of hole = 3 × radius of post

Step 2:

The next thing you should do is calculate the volume of the post section that will be submerged inside the hole. To achieve this, use this simple formula, For a rectangular, volume (V)= length × width × depth, and for a cylindrical hole, use the formula, volume (V) = radius² (r²) × π × depth.

Step 3:

Finally, to calculate the volume of concrete needed, you need to subtract the post volume from the hole volume. After the subtraction, you have the volume of concrete needed per fence post.

To calculate the total volume of concrete needed for all the fence posts, multiple the volume of concrete per fence post by the number of fence posts you have. Add a little concrete to the total volume to cover for spillage.

What is the Best Concrete Mix for a fence post?

A good concrete mix does not need to be mixed; it should be easy to work with, it should have a good and sturdy setting.

When using a concrete mix, all you need to do is pour the mixture into the hole and soak it with water. 

Factors that may determine the concrete mix you use include the soil type, size and type of fence post, and weather.

The best concrete mix for a fence post is the quikrete concrete mix in a 50lb bag. This concrete is affordable as it can be purchased from a local store or online for just $6.

It also saves you the labor of using too much time and hand tools. It takes about 20 to 40 minutes to set, which is fast; full hardening will be achieved in 28 days at 4000psi.

Does Soil Condition Matter?

Yes, the soil condition matter greatly when installing a fence post. Sandy soil is easy to dig, which is great, but they tend to collapse easily. To solve this problem, wet the soil to aid compaction with more stable soil.

Loamy may be the best and easiest soil to work within fence installation. It is easy to dig, and it does not crumble; the softness of this soil makes a significant impact on the strength of the soil.

Clay is strong, which makes it difficult to dig; it also shrinks, making your fence post unstable after installation.

How to Install Fence Post in Concrete

The steps involved in installing fence posts in concrete are straightforward. The steps below should guide you through the installation.

Step 1:

Dig up a ⅓ the height of your post

Step 2:

The width of your hole should be three times the diameter of your post

Step 3:

Get your concrete mix and pour it into the hole. Soak the concrete in water.

Step 4:

Submerge ⅓ of your fence post into the concrete.

Step 5:

Give the concrete 20 to 50 minutes to set.

How Much Concrete For a 3 × 3 Fence Post?

The amount of concrete needed leans on the hole and post’s height, depth, and width. We have given a detailed guide on manually calculating the volume of concrete needed above.

A 3 × 3 fence post will need 1½ 50lbs bag of concrete. You can decide to mix the concrete yourself or use a concrete mix that is way easier.

How Much Concrete For a 4 × 4 Fence Post?

With proper calculation, you will discover that your fence post needs 2 to 3 bags of concrete. You can choose to use a post concrete calculator to determine the amount of concrete needed, or you can manually calculate the amount.

How Much Concrete For a 6 × 6 Fence Post?

From the previous sections, it is clear thAt as the size of the fence post increases, the amount of concrete needed to install the fence post also increases.

For a 6 × 6 fence post, you will need about 4 to 5 bags of concrete to keep your fence post stable and sturdy. Always remember to consider factors like soil type and weather.


Determining the amount of concrete needed to install a fence post can be confusing sometimes. But we have provided a guide to ease your work.

The best type of concrete for installing fence posts is reinforced concrete, but a more affordable choice is the quikrete concrete mix.

We have also learned that soil conditions matter when installing a fence post. The amount of concrete needed depends on the size of your post; for a standard-sized post, you need about 4 to 5 bags of 50lb concrete.

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We trust this article helped you know how much cement for fence post. You may also want to check out the if You Can Use A Finish Nailer For Fencing?

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