Calculate exactly how many type of yards or just how many bags of concrete you’ll need for a collection of article holes by entering the post diameter and also hole size.

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If you’re not sure what dimension hole to dig, a dominion of thumb is to use a hole diameter three times the write-up diameter and 1⁄3 as deep as the write-up height. See listed below for even more indevelopment.


Typical is $115 per yd3, although your price will vary based on the type of concrete, merchant, and area.
Use the article hole estimator to conveniently discover out how a lot concrete you will certainly must set your fence articles. Get in your short article and also hole dimensions in any type of units.

The calculator will provide you the results in cubic yards and the number of pre-mixed bags of concrete (40 lb, 60 lb, and 80 lb bags).

To encertain that your write-ups are sturdy for a lengthy time to come, remember to make your holes 3 times the diameter of your short article and also 1⁄3 as deep as your fence. So, a 6’ high fence demands holes a minimum of 2’ deep.

Order added material to account for settling and spillage. If you have actually many articles to set, it may pay you to mix the concrete yourself. Or, if you need a cubic yard or even more, order blended and also delivered.

Concrete building contractors deserve to provide estimates for moving and installing cement for your post project.


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Illustration reflecting a short article hole via a diameter that is three times the post’s diameter and with a depth that is 1/3 the height of the write-up.

How to Find the Amount of Concrete Needed

Concrete is marketed pre-made (and also normally delivered) by the cubic yard or in pre-combined bags by weight.

To calculate how a lot concrete you require, you need to recognize the article size you are going to use and exactly how many type of posts you are installing. Your article diameter and elevation determine how substantial each hole demands to be.

As stated over, fence post holes must be 3 times the diameter of your article and also 1⁄3 as deep as your article.

First, you have to calculate the volume for the article hole. Then calculate the volume for the component of the article that will be subunified in the hole. Make sure all your units are the same!

To quickly use the table above, transform your units to feet if they aren’t currently. Use our calculators to quickly transform transform inches, yards, or meters to feet.

Blog post Hole Volume Formulas

Use these formulas to calculate volume or, for round holes, use our cylinder cubic yardage calculator.

Rectangle: volume = size x width x depthCylinder: volume = radius2 x π x depth (π = 3.14)

Calculate Concrete Volume

With the volume of the subunified write-up and also the volume of the hole figured out, subtract the short article volume from the hole volume, and you will have the volume of concrete needed for each hole. Sindicate multiply that amount times the number of write-ups to get a complete quantity. Don’t forgain to add in some added for spillage and waste.

If you have actually multiple different dimension article holes to fill, calculate each collection with corresponding dimensions individually, then include the totals together.

Example Fence Blog post Concrete Calculation

Let’s usage an example to illustrate what we extended over. Let’s say we are installing a 6’ fence. Therefore, 2’ of the post will be in the ground. You require twenty (20) 4” nominal round short articles. Note that 4” write-ups are actually 3 ½” in diameter. Use the formulas above for volume.


Calculate the post volume

Change short article diameter to feet:

3.5” / 12 = 0.2917’

Find radius (½ of the diameter):

0.2917’ / 2 = 0.1458’

Volume of round post:

(0.1458’)2 x π x 2’ = 0.1336 cubic ft.


Calculate the hole volume

Hole radius (3x short article radius):

3 x 0.1458’ = 0.4374’

Volume of post hole:

( 0.4374’)2 x π x 2’ = 1.2026 cubic ft.


Calculate concrete volume

Hole volume – post volume:

1.2026 – 0.1336 = 1.069 cubic ft. per post

TOTAL volume concrete:

1.069 cubic ft x 20 articles = 21.38 cubic ft.

Convert to cubic yards:

21.38 cubic ft. / 27 = 0.79 cubic yards

Hint: you have the right to also usage a concrete calculator for this step.


You could uncover it easier to transform the cubic footage to cubic yards; if so, divide the cubic footage by 27.

Many concrete providers will not offer fractions of a yard of concrete, though it is worth asking about. So, in this example, you would certainly desire to buy bags. Using the table listed below, you would should buy at leastern eight 80 lb. bags and one 40 lb. bag (yielding a complete of 5.1 cubic feet) of concrete to permit enough for added.


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Pre-Mix Bag Concrete Yield

The following table reflects the approximate yield of mixed concrete for widespread bag weights.

Approximate yield for miscellaneous bags of concreteBag Concrete WeightMixed Concrete Yield (approximate)
40 lb (18.1 kg)0.30 cu ft (8.5 L)
60 lb (27.2 kg)0.45 cu ft (12.7 L)
80 lb (36.3 kg)0.60 cu ft (17 L)

Tips For Ordering Concrete

Consider these tips to ensure your concrete installation goes smoothly.

Type of concrete and its appropriate installation

This relies on the application and also the climate wright here you live. Colder temperatures need much longer curing times; sandy soils need different shaped holes; more too much freeze/thaw cycles require better strength concrete than more temperate regions.

Your concrete supplier deserve to advise you on the proper mix to usage for your task and also region.

More costs

For ready-mix concrete distribution, there are generally added fees for distribution, weekend business, little lots, and also overtime for long unloading times. Discuss these concerns via your concrete supplier ahead of time so that you have actually a clear knowledge of expenses and also have the right to plan as necessary.

Further concrete

Order extra concrete (overage) for your project. The amount of overage you setup for will vary based on your quantity, but setup for at leastern 10% overage to accommoday spillage, settling, and grading inconsistencies.

This will certainly conserve you from a poor pour (concrete set up in parts causing a separated, weak mass) in the occasion that your estimates are even slightly off.

Allocate sufficient time

Finally, digging can be tough, time-consuming work. Allow plenty of time to dig all the post holes for the project before the concrete is yielded or blended.

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Mixed concrete that need to sit before being poured into location have the right to partially or also fully set. This deserve to result in significant waste from hardened, unoffered concrete or develop air pockets and also endangered strength from pouring concrete that is too thick.