Reinforcing bars, better known as rebar, are bars made of steel that you put in place before you pour concrete. The rebar strengthens the concrete and prevents the concrete from falling apart. The amount of rebar that is used varies by local building codes, so there is no set amount of rebar required that is universal.
Contact your local building department and ask them for the required amount of rebar needed. Specify what sort of structure, as requirements can be different for different parts of construction, such as floors, walls or partitions. They will tell you the amount of rebar required per square foot of concrete.
Measure the size of the concrete slab for which you want to calculate the rebar amount. For easier calculations, take the measurement in feet.
Calculate the square footage of your concrete slab. For rectangular slabs, multiply the width by the length.
Multiply the square footage of the concrete slab by the amount of rebar required per square foot. This will give you the amount of rebar in your concrete.