Hole Volume Calculator

What Is a Hole Volume Calculator?

A hole volume calculator finds how much space a circular or rectangular excavation occupies. It is useful for fence post holes, footing digs, utility trenches, and any project where you need to know excavation volume or how much concrete to order.

Circular Hole Volume Formula

For a cylindrical hole, volume equals the base area times depth:

$$ V = \pi \times r^2 \times h $$

Where $r$ is the radius and $h$ is the depth. If you know diameter instead, divide by 2 to get the radius. This is the same formula used by the Cylinder Calculator.

Rectangular Hole Volume Formula

For a rectangular excavation, multiply length, width, and depth:

$$ V = l \times w \times h $$

This matches the Rectangular Prism Calculator and is common for footing pads, pier forms, and trench sections.

Concrete Volume for Post Holes

When filling holes with concrete for fence posts or deck footings, multiply the total hole volume by the number of holes and add a waste allowance (typically 5% to 10%) to account for spillage and uneven ground:

$$ V_{\text{concrete}} = V_{\text{hole}} \times (1 + \text{waste}) \times n $$

For larger cylindrical pours, try the Concrete Cylinder Calculator or Concrete Column Calculator. For general concrete estimates, use the Concrete Calculator.