Concrete Calculator

What this calculator does

The Concrete Calculator estimates the volume of concrete required for slabs, footings, pads, and similar rectangular pours. It helps convert project dimensions into cubic volume for ordering material.

How to use the calculator step by step

Enter the length, width, and thickness using the units shown on the page. Check that thickness has been converted correctly if the form expects feet rather than inches. Select Calculate to see the estimated concrete volume.

How the calculation works

For a rectangular slab, volume equals length × width × thickness. The result is then converted into cubic yards or another displayed unit. A 10 ft × 10 ft slab that is 4 inches thick has a volume of about 33.33 cubic feet, or 1.23 cubic yards.

Worked example and scenario testing

For a 12 ft by 20 ft patio at 4 inches thick, convert 4 inches to 0.333 feet. The volume is about 79.9 cubic feet. Dividing by 27 gives about 2.96 cubic yards before adding waste.

How to interpret your result

The result is the geometric volume of the shape entered. Real orders are often slightly larger to allow for uneven excavation, spillage, settlement, and measurement error.

Accuracy, assumptions, and limitations

This calculator does not automatically model irregular shapes, reinforcement displacement, sloped slabs, deepened edges, or variable excavation unless those inputs are specifically provided.

Common mistakes to avoid

The most common mistake is entering inches as though they were feet. Also avoid ordering exactly the theoretical volume with no allowance for site variation.

Privacy and browser-based calculations

Only project dimensions are processed in the browser. No identity or account information is needed.

Frequently asked questions