🕳️ Hole Volume Calculator
Calculate the volume of a round or square hole, useful for post holes, footings, and fence posts.
1
2
in
3
in
4
in
5
holes
What this calculator does
This tool calculates the volume of one or more holes — round or square — which is useful for figuring out how much concrete, gravel, or backfill you need for post holes, footings, and similar excavations.
The formula
For round holes, area = π × radius². For square or rectangular holes, area = width × length. Volume = area × depth, multiplied by the number of holes, with results also converted to cubic yards and gallons.
This calculates the geometric volume of the hole itself; actual concrete needed may be less if a post occupies part of the volume. Subtract the post’s own volume for a precise concrete order.
Last reviewed August 2026