Concrete Slab Calculator

Dimensions

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Pouring more than one slab? Give this one a label and add it — the results panel keeps a running grand total.

FAQ

How thick should a concrete slab be?

4 inches (10 cm) is standard for patios, walkways, and shed floors. Driveways carrying vehicles typically use 5–6 inches, and areas with heavy trucks go to 6–8 inches.

Do I need reinforcement (rebar or mesh)?

Most slabs 4 in. or thicker benefit from welded wire mesh or rebar to control cracking. This calculator estimates concrete volume only — reinforcement is sized separately.

Can I calculate concrete by square footage instead of length and width?

Yes — if you already know the square footage, enter it as Length with Width set to 1 (in the same unit), or enter any length/width pair that multiplies to your square footage. The slab thickness input works the same either way.

How much does a concrete slab weigh?

Normal-weight concrete runs about 150 lb per cubic foot (≈2,400 kg/m³). The results panel above shows an estimated total weight for your slab alongside the volume — useful for checking what a delivery truck, crane, or structure needs to support.