Broadening of the diffraction reflections in nanocrystalline powders of nonstoichiometric niobium carbide NbC0.93 with the average particle size from ~200 to ~2000 Å has been studied by the neutron diffraction method. The functional dependence of the broadening W2 on the interplanar distance d2 has been obtained including size, deformation, and inhomogeneous broadening. The average size of the coherent scattering regions and microstrains in crystallites with allowance for the anisotropy of the deformation distortions have been estimated.