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## Amazing! Updated! How Much Concrete You Need For A Fence Post (Calculator)

## Information about Updated! How Much Concrete You Need For A Fence Post (Calculator)

When installing a fence post, the amount of concrete needed is calculated based on the diameter of your fence post and the height of the post above the ground.

Most fence post holes require between 1 – 4 bags of concrete to hold the post securely in place.

The best way to determine the size of the hole is:

- The diameter of the hole is 3 times the width of the fence post
- The depth of the hole is one-third to one-half the height of the fence post above ground

**For example: a 6 ‘tall 4 “x 4” fence post would need a hole 12 “in diameter and about 2’ to 3 ‘deep. That would require four 50 pound bags of quick-setting concrete mix per fence post.**

## How much concrete for a 3 inch diameter fence post?

A 3 “diameter fence post needs a post hole that** 9 “in diameter** and a depth of at least 1/3 the height of the post from the ground. A 6 ‘high post needs a 2’ deep hole.

For a 9-inch diameter hole, the table below will tell you how many bags of concrete you will need based on the depth of your hole.

Hole depth in inches

10-12 inches

14 – 26 inches

27-36 inches

Number of 50 pound bags of concrete needed

1

2

3

These numbers are based on a fence post that is 6 ‘above the ground and 2’ below the ground.

## How much concrete for a 4 “diameter fence post?

A 4 inch diameter fence post needs a post hole that **12 “in diameter** and a depth of at least 1/3 the height of the fence post above ground.

The table below shows you how many bags of concrete you will need per post for a hole that is 12 “in diameter and between 12” and 36 “deep.

Hole depth in inches

10-14 in

16-22 inches

24-30 inches

32-36 inches

Number of 50 pound bags of concrete needed

2

3

4th

5

These numbers are based on a fence post that is 6 ‘above the ground and 2’ below the ground.

## How much concrete for a 6 inch diameter fence post?

A fence post that is 6 inches in diameter should have a post hole that **18 “in diameter** and a depth that is at least 1/3 the height of the post above ground.

The table below shows you how many bags of concrete you will need per fence post for a hole 18 “in diameter and between 10 and 36” deep.

Hole depth in inches

10-12 inches

13-17 inches

18-21 inches

22-25 inches

26-28 inches

28-30 inches

32-36 inches

Number of bags of 50 lb. Concrete needed

4th

5

6th

7th

8th

9

11

These numbers are based on a fence post that is 6 ‘above the ground and 2’ below the ground.

### Post Hole Concrete Calculator

This concrete calculator will help you find out how many bags of concrete you will need per post hole.

Enter the diameter of your post, then the diameter and depth of your post hole.

Next, enter how many post holes you need to fill and click “**calculation**“.

The concrete calculator tells you how many cubic meters of concrete you need. (just in case you have a lot of holes to do.)

Using ready-mixed concrete may be a better solution than using bagged concrete when you are busy.

The calculator also tells you how many 50 lb., 60 lb. and 80 lb. Bags of concrete you will need.

This will give you a chance to use a larger bagged concrete mix than what is indicated in the tables above and know how much to get.

You can order 1 cubic meter of ready-mixed concrete, but understand that the concrete company will bill you for a small load, which can be several hundred dollars.

Most concrete companies charge some sort of small load fee for all orders under 5 cubic meters.

Call your local pre-fab mixer to find out what’s billed in your area.

How many concrete sacks do you need for a post hole?

### 7 steps to setting a fence post in concrete

**STEP 1.** Using a Post hole excavator, dig your post hole so the diameter is three times the width of your fence post.

Example: For a 4 “wide post you will need to dig a 12” diameter hole.

The depth of the hole should be at least 1/3 the height of the post above ground.

Example: For a post 6 ‘above the ground you should dig a hole that is 2’ deep.

If you have a lot of holes to dig, this one Gas powered posthole dredger will be much faster.

**STEP 2.** Add about 6 “gravel into the bottom of the hole.

Compact the gravel by tamping it with your post or using a 2 x 4.

If you don’t have your own gravel, use something like Quikrete gravel.

**STEP 3. **

Place the fence post in the center of the hole and attach some 2 x 4 braces to hold it in plumb.

You can also use this post bracing kit to hold the fence post in place while the concrete is being put in place.

the Post kit is available from Amazon.

**STEP 4.**

Use one even to plumb the post vertically.

Once the post is in place, use your 2 x 4 or the post kit to attach the post.

You don’t want the post to be off plumb when the concrete starts to build up.

**STEP 5. **

Fill the hole with a quick-setting concrete mix.

Use enough dry concrete to fill the hole to about 3-4 “below the ground.

**STEP 6.**

Wet the concrete by adding about a gallon of water for every 50 pound bag of concrete mix.

Let the water slowly soak into the concrete and completely saturate it.

The quick-setting mixture will harden in about 20-40 minutes.

**STEP 7.**

Let the concrete sit for at least 4 hours before you start building your fence.

If you’ve used a quick-set concrete mix, it will be strong enough to support the weight at this point.

If you’ve used regular concrete mix, wait until the next day to start building your fence.

#### What is the best concrete mix for fence posts?

The two best concrete mixes for setting fence posts in my opinion are:

Both concrete mixes are an “add water only” type of concrete. That means you don’t have to premix the concrete before putting it in the hole.

Both are set up in 20 to 40 minutes, which speeds up your fence installation.

If you’re in no hurry, any regular concrete mix will work fine. Using a regular setting mix instead of a quick mix means all you have to do is wait until the next day to start building the fence.

#### Should fence posts be set in concrete?

Your fence will only be as strong as the posts that support it. In most cases, it’s much better to embed your fence posts in concrete.

Regardless of whether you have fence posts made of wood or metal, setting them in concrete gives you a stable base for your posts.

Here are a couple of things to keep in mind, though **specify your contributions:**

- If you choose a wooden fence post, pressure treated posts will give you the best long term performance. Cedar and redwood stakes are also very good as they both have natural resistance to rot and rot.
- If you are using a spruce, oak, or pine wooden post, be sure to treat the wood with a wood preservative such as Rust-Oleum Woodlife Underground wood preservative or the post will rot and break.
- Make sure you use pea gravel or crushed stone under the concrete to allow rainwater to drain into the surrounding soil and not build up around the fence post.
- Taper the top of the concrete away from the embedded fence post to help drain rainwater away from the post. The less water that gets between the concrete and the post, the better.
- Caulk the seam around the post where it comes out of the concrete. If you notice a small seam where the wood has shrunk from the concrete, use something Acrylic latex seal to fill the seam and prevent water from entering.

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Category – Concrete