Hole Volume Calculator: Cylindrical and Rectangular Holes

Your details

Choose cylindrical for round post holes, rectangular for square footings or trenches.
The diameter of the round hole at the top (same all the way down for a straight hole).
in
How deep the hole is, measured straight down from ground level.
in
Multiply by this many identical holes (e.g. a fence line with 10 posts).
holes
Extra material to order to account for spills and mixing losses. 10% is the industry standard.
%
The weight of the pre-mixed dry concrete bags you plan to buy.
Hole volume
2.36ft³

Volume of a single hole

Hole volume0.087yd³
Hole volume0.0667m³
Total volume (all holes)2.36ft³
Concrete needed (with waste)2.59ft³
Concrete needed0.096yd³
Bags needed5bags
Radius (ft)0.5
Depth (ft)3
Single hole (ft3)2.36
All holes total (ft3)2.36
With waste allowance (ft3)2.59

One round hole: 2.36 ft3

  • Each hole holds 2.36 ft3 (0.0667 m3).
  • With the 10% waste allowance you need 2.59 ft3 of concrete, or about 0.096 yd3.
  • That equals 5 bags of 80-lb pre-mixed concrete (rounded up to the nearest whole bag).

Next stepFor fence posts, the rule of thumb is to make the hole diameter at least 3 times the post diameter and the depth at least one third of the above-ground post height.

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