We present empirical potential and Density Functional Theory results of interstitials in FeCr and pure Cr. Results show that potentials for the original and revised two-band model, a recently introduced third two-band model, and for the revised concentration-dependent model produce errors of up to multiple eV in formation and binding energies for Fe-containing interstitials in pure Cr. Fe-interstitial binding in Cr is much stronger than Cr-interstitial binding in Fe according to Density Functional Theory, but all four potentials still strongly overestimate the binding strength. At the Fe-rich end errors in empirical potentials are smaller and most of the errors are not a linear extrapolation in concentration of the larger errors in pure Cr. Interstitial formation energies in Fe-rich FeCr are underestimated by all four empirical potentials, but much less so than in pure Cr. In Fe-rich FeCr the revised concentration-dependent model produces Cr-interstitial binding energies quite similar to Density Functional Theory values, while all three two-band models show almost no binding or repulsion.