Calculate how many cubic yards and pre-mixed bags of concrete you need for slabs, patios, footings, and sidewalks.
There are 45 bags of 80 lb concrete in one cubic yard (27 cubic feet / 0.60 cu ft per bag = 45 bags).
Standard residential walkways, patios, and shed slabs are poured 4 inches thick (using 2x4 lumber for formwork). For heavy pickup trucks or RV pads, a 5-inch or 6-inch reinforced pour with rebar is recommended.
Subgrades and gravel bases are rarely perfectly level. Subgrade depressions, spills, and form deflection routinely consume 8% to 10% more volume than theoretical math estimates.