Construction

An 80-lb bag yields about 0.6 cubic feet, while a 60-lb bag yields 0.45 cubic feet. Divide your total cubic feet by the yield per bag, then add 5-10% for waste.

One cubic yard equals 27 cubic feet. Concrete is typically sold by the cubic yard for large projects, but bags are measured in cubic feet yield.

For projects under 1 cubic yard, bags are convenient but labor-intensive. Above 1-2 yards, ready-mix delivery is more cost-effective and saves hours of mixing.

Standard slabs are 4 inches for walkways and patios, 5-6 inches for driveways and garages. Footings and structural elements require engineer-specified depths based on load and soil conditions.

Concrete waste accounts for spillage, uneven subgrade, and over-excavation. A 5-10% allowance ensures you don't run short mid-pour, which can compromise the project.

The calculator is accurate when you enter correct dimensions and choose the right shape and thickness. Results are theoretical volume and do not account for subgrade irregularities, form bulge, or spillage unless you add a waste factor. For ready-mix, rounding up to the next 0.25–0.5 cubic yard is common to avoid coming up short.

It computes concrete volume from your measurements by applying standard geometry (length × width × thickness for slabs, and shape-specific formulas for footings, columns, or holes). It then converts that volume into common ordering units such as cubic yards, cubic feet, or number of bags based on the bag yield you select. Any additional allowance is applied as a percentage increase to the calculated volume.

Yes—use the cylinder or round-hole option and enter the diameter and depth of each pier or hole. Multiply by the number of holes to get total volume, or calculate one and scale up. If the hole flares or is irregular, use the average diameter and add extra allowance.