**Estimating the amount of re-bar??? - Structural ...**

May 21, 2008· The calculation you provided would only apply if your foundation was solid steel! Since it is an estimate you could consider minimum reinforcing per ACI 10.5.1 or simply 0.00333 x bw x d therefore if you have a 4' square footing x 18" your min reinf would be 48" x 18" x 0.00333 = 2.877 in^2 x 48" length (discounting cover because it is an estimate) x 2 (for each direction) = 276 in^3 / 1728 in ...