Concrete Calculator

Estimate concrete volume, cubic yards, bag quantities, waste allowance, and optional material cost for slabs, post holes, and footings.

Project Details

Project Type

Length (ft)

Width (ft)

Thickness (in)

Quantity

Hole Diameter (in)

Hole Depth (in)

Post Diameter (in) — Optional

Number of Holes

Length (ft)

Width (ft)

Depth (in)

Number of Footings

Waste and Bag Estimate

Extra / Waste (%)

Bag Size

Price Per Bag ($) — Optional

Concrete Estimate

Enter your project measurements and click Calculate Concrete.

Concrete requirements are rounded for planning purposes. Actual quantities may vary because of excavation shape, uneven subgrade, form dimensions, spillage, and job-site conditions.

How the Concrete Calculator Works

The calculator determines the volume of the selected project and converts it into cubic feet and cubic yards. It then applies the selected waste allowance and estimates the number of concrete bags required.

Cubic Yards = Length × Width × Depth ÷ 27

How Much Extra Concrete Should You Order?

A 10% allowance is a useful starting point for many small projects. Irregular excavation, uneven ground, deep post holes, spills, and form movement may require additional material.

Bagged Concrete or Ready-Mix?

Bagged concrete is convenient for smaller projects and repairs. Larger slabs, long footings, and projects requiring many bags may be easier and more economical with ready-mix concrete delivered by truck.

Before You Pour

If the project drawings specify a reinforcing grid, estimate a slab rebar grid from specified spacing separately from the concrete volume. Neither quantity estimate supplies a structural design. For a triangular plan area, calculate volume for a triangular plan area using the intended thickness and confirm the volume basis before ordering concrete.

Confirm required slab thickness, footing dimensions, reinforcement, frost depth, drainage, and applicable building requirements before purchasing material.