Enter the diameter and depth of the post hole into the calculator to determine the volume of the hole. This calculator helps in estimating the amount of material needed to fill the hole or the amount of soil to be removed.

Post Hole Size Formula

The following formula is used to calculate the volume of a post hole.

V = π * (D/2)^2 * H

Variables:

  • V is the volume of the post hole (cubic inches)
  • D is the diameter of the post (inches)
  • H is the depth of the hole (inches)

To calculate the volume of a post hole, use the formula where V equals π times the square of half the diameter (radius) times the depth (H).

What is a Post Hole Size?

A post hole size refers to the volume of the cylindrical space dug into the ground to accommodate a post for fences, signs, or other structures. The size is important to ensure stability and strength of the post, and it is typically determined by the diameter and depth of the hole required for the specific application.

How to Calculate Post Hole Size?

The following steps outline how to calculate the Post Hole Size.


  1. First, measure the diameter of the post (D) in inches.
  2. Next, determine the depth of the hole (H) in inches.
  3. Use the formula V = π * (D/2)^2 * H to calculate the volume (V).
  4. Finally, calculate the volume of the post hole in cubic inches.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Diameter of the post (D) = 6 inches

Depth of the hole (H) = 24 inches