  A central challenge in high throughput density functional theory (HT-DFT)
calculations is selecting a combination of input parameters and post-processing
techniques that can be used across all materials classes, while also managing
accuracy-cost tradeoffs. To investigate the effects of these parameter choices,
we consolidate three large HT-DFT databases: Automatic-FLOW (AFLOW), the
Materials Project (MP), and the Open Quantum Materials Database (OQMD), and
compare reported properties across each pair of databases for materials
calculated using the same initial crystal structure. We find that HT-DFT
formation energies and volumes are generally more reproducible than band gaps
and total magnetizations; for instance, a notable fraction of records disagree
on whether a material is metallic (up to 7%) or magnetic (up to 15%). The
variance between calculated properties is as high as 0.105 eV/atom (median
relative absolute difference, or MRAD, of 6%) for formation energy, 0.65
{\AA}$^3$/atom (MRAD of 4%) for volume, 0.21 eV (MRAD of 9%) for band gap, and
0.15 $\mu_{\rm B}$/formula unit (MRAD of 8%) for total magnetization,
comparable to the differences between DFT and experiment. We trace some of the
larger discrepancies to choices involving pseudopotentials, the DFT+U
formalism, and elemental reference states, and argue that further
standardization of HT-DFT would be beneficial to reproducibility.
