How much metal goes in a 20ftx18ft x4in thick concrete floor?

To determine the amount of metal (reinforcement, like rebar) needed for a concrete floor, you first need to calculate the volume of concrete. For a 20 ft x 18 ft area with a thickness of 4 inches (or 1/3 ft), the volume is 20 x 18 x (1/3) = 120 cubic feet. The amount of rebar required depends on the design specifications, but a common approach is to use about 1 to 1.5% of the total concrete volume in rebar, which would equate to approximately 1.2 to 1.8 cubic feet of metal. However, the specific amount of rebar may vary based on load requirements and local building codes.