Concrete Slab Calculators

A concrete slab calculator converts the length, width and thickness of a flat pour into cubic yards of ready-mix — or into the number of 40, 60 or 80-lb bags to buy. Enter the dimensions once and the estimate updates as you type, so you can compare a 4-inch patio against a 6-inch driveway in seconds.

How thick should the slab be? Four inches is standard for patios, walkways and shed floors; five to six inches for driveways and anything that carries vehicles. Whatever you pick, the calculators below also suggest ordering about 10% extra for uneven subgrade and spillage.