Hole Volume Calculator

The Hole Volume Calculator finds the total volume of a dug hole — useful for estimating how much concrete, fill, or material you'll need for fence posts, footings, or any excavation project. Select your hole shape (circular or rectangular), enter the diameter or length and width, and set the depth to get the hole volume in your preferred unit. Secondary outputs include concrete bags needed (60 lb bags), concrete volume in cubic yards, and hole surface area.

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Results

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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Frequently Asked Questions

How do you calculate the volume of a circular hole?

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).

How do you calculate the volume of a rectangular hole?

For rectangular holes, use: Volume = length × width × depth. Simply multiply all three dimensions together to get the total volume.

How much concrete do I need to fill a hole?

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.

What's the difference between diameter and radius?

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.

Can I use this calculator for post holes?

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.

How accurate are the concrete bag estimates?

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.

What units can I use for measurements?

The calculator supports inches, feet, centimeters, and meters for length measurements. Volume can be displayed in cubic inches, feet, meters, gallons, or liters.

Do I need to account for soil expansion when backfilling?

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.