In this talk, recent progress on two studies in which the accuracy of a calculation is assessed as a function of typical input parameters used in planewave DFT (e.g. planewave cutoff energies, k-point mesh) on computed properties (e.g. lattice constant, cohesive energy, bulk modulus) will be presented. In the first study, the lattice constant and bulk modulus are examined for a series of calculations on atomic solids in various crystal structures. In the second study, convergence of derived properties with respect to the number of k-points used to sample the Brillouin zone, the smearing method used, and the magnitude of the smearing parameter is examined. Using the information from these studies, it is hoped that computational scientists will have the means to make well-informed choices about their input parameters and a greater understanding of the consequences.