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`V = pi * ( "HW" /2)^2 * "HD" - pi*( "PW" /2)^2* "HD" `

Enter a value for all fields

The **Concrete for a Post Hole** calculator computes the volume (**V**) of concrete needed around a circular post in a circular hole.

**INSTRUCTIONS:** Choose units and enter the following:

- (
**HD**) Depth of the Hole - (
**HW**) Width of the Hole - (
**PW**) Post Width

**Concrete to Fill Post Hole (V):** The calculator returns the volume in cubic yards. However this can be automatically converted to other volume units via the pull-down menu.

The formula for the volume of a circular column is:

V = π•r²•h•n

where:

- V = Volume of the column
- r = radius of the base
- h = height of the column
- n = number of columns or piers

This calculator subtracts the column defined for the post from the column defined for the whole.

**Related Calculators:**

Augers are often used to drill post holes. After the hole is dug, it's ideal to put a little gravel at the bottom of the hole for water drainage during wet seasons. Then place the post in the hole and surround it with concrete to truly anchor the post.

For the DIY crowd that mixes their own concrete, vCalc provides a tool to convert volume in cubic units (cubic feet, yards or meters) to the number of bags of concrete in the following sizes:

- 40lb bags
- 60lb bags
- 80lb bags

Take the answer from this calculator and enter it in the Concrete Bags from Volume calculator (CLICK HERE).