Concrete Calculator

An 80 lb bag of concrete mix makes approximately 0.60 cubic feet. Divide your total cubic feet by 0.60 to get the number of bags needed. Always add 10% extra for waste and spillage.

For a typical residential driveway, 4 inches is standard. Sidewalks and patios also typically use 4 inches. Slabs that will support heavy vehicles or equipment should be 5–6 inches thick with rebar reinforcement.

Calculate the volume in cubic feet (length × width × depth, all in feet), then divide by 27 to convert to cubic yards. Most ready-mix concrete is ordered and priced by the cubic yard.

Concrete reaches about 70% of its design strength in 7 days and approximately full strength at 28 days. Foot traffic is generally safe after 24–48 hours; vehicles should wait at least 7 days.