Enter your hole shape, dimensions (diameter or width/length), and depth to calculate the hole volume, surface area, and exactly how many 60 lb concrete bags you'll need to fill it — so you're not making an extra hardware store run.
Hole Volume
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Concrete Bags Needed (60 lb)
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Concrete Volume
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Hole Surface Area
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To calculate circular hole volume, use the formula: Volume = π × radius² × depth. Measure the radius (half the diameter) and depth of the hole, then multiply by π (3.14159).
For rectangular holes, use: Volume = length × width × depth. Simply multiply all three dimensions together to get the total volume.
Calculate the hole volume first, then convert to cubic yards (divide cubic feet by 27). A standard 60-lb concrete bag covers about 0.45 cubic feet when mixed.
Radius is the distance from the center to the edge of a circle. Diameter is the distance across the entire circle through the center, which is twice the radius.
Yes, this calculator works perfectly for fence post holes, mailbox posts, or any cylindrical excavation. Just enter the diameter and depth of your post hole.
The estimates assume standard 60-lb concrete bags and account for typical mixing ratios. Always buy 10-15% extra material to account for waste and variations.
The calculator supports inches, feet, centimeters, and meters for length measurements. Volume can be displayed in cubic inches, feet, meters, gallons, or liters.
Excavated soil typically expands 15-25% in volume. This calculator gives the exact hole volume, but you may need less backfill material than the calculated volume suggests.