Concrete calculator

Use 4 inches as a common starting point for patios, walks, and small pads; use 5 inches for a passenger-car driveway and 6 inches for heavier use. Soil, reinforcement, freeze conditions, and local requirements can change the final depth.

Plan on a compacted gravel base when the soil does not provide firm, even support and drainage. About 3 to 4 inches is a common starting point for small residential slabs, but weak soil, frost, and heavier loads may require more.

Use the reinforcement required by the slab plan, expected loads, soil, and local rules. Rebar, mesh, or fiber can help manage cracking, but none replaces the correct depth, compacted base, control joints, or curing.

Divide the slab into panels that are as close to square as practical, and cut joints at least one-quarter of the slab depth. For a 4-inch patio or walk, keep the spacing around 10 feet or less and make the cuts as soon as the concrete is hard enough not to tear at the edges.

Keep people off standard concrete for at least 24 to 48 hours and cars off a new driveway for at least 7 days. Keep the slab moist or protected for the curing period required by the mix and weather; concrete continues gaining strength for about 28 days.

No. This is a material planner for residential flatwork such as patios, sidewalks, small pads, slabs, and driveways. Structural work needs local code and professional guidance.