Slabs, bags, yards

Concrete Calculator

Estimate concrete volume, bags, ready-mix yards and cost before you buy materials.

US units 10% default waste Bag and yard estimates

Concrete estimate

Enter dimensions

Estimate assumptions

Estimates are for planning and ordering only.
Bag counts are rounded up to whole bags.
Ready-mix yards are rounded up to the nearest 0.25 cubic yard.
Default waste is 10%. Increase it for uneven excavation, spillage, or complex forms.
Verify structural work with a contractor, engineer, or supplier before pouring.

Fast concrete estimates for common jobs

Use the calculator for patio slabs, sidewalks, small pads, fence posts, deck footings and tube forms. Results show cubic feet, cubic yards, bag count and optional cost.

The first number to trust is the rounded-up result. Concrete jobs are difficult to fix if you order short, so the calculator includes a waste factor by default.

What the result includes

Concrete volumeThe raw cubic feet needed for the dimensions entered.
Waste factorAn added percentage for spillage, uneven forms and small ordering errors.
Bags to buyWhole bag count based on the selected bag size and yield.
Ready-mix yardsCubic yards rounded up to the nearest quarter yard.

Common next purchases

Concrete mix Rebar Tube forms Mixing tools Trowels and floats

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FAQ

How much concrete do I need?

Enter the shape and dimensions. The calculator returns cubic feet, cubic yards, bags and ready-mix yards with waste included.

Should I order extra concrete?

Yes. A 10% waste factor is a common planning default for small jobs. Increase it for uneven subgrade or complicated forms.

Does this replace a contractor estimate?

No. Use it for planning and material estimates. Structural or code-sensitive work should be checked by a qualified professional.