FeCr2O4 crystallizes in the orthorhombic Cmcm space group. Cr(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of edge and corner-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles range from 0-56°. Fe(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a square co-planar geometry to four equivalent Cr(1) atoms. In the second O site, O(2) is bonded to two equivalent Cr(1) and two equivalent Fe(1) atoms to form OCr2Fe2 tetrahedra that share corners with two equivalent O(2)Cr2Fe2 tetrahedra, corners with ten equivalent O(3)Cr3Fe2 trigonal bipyramids, and edges with two equivalent O(3)Cr3Fe2 trigonal bipyramids. In the third O site, O(3) is bonded to three equivalent Cr(1) and two equivalent Fe(1) atoms to form distorted OCr3Fe2 trigonal bipyramids that share corners with five equivalent O(2)Cr2Fe2 tetrahedra, corners with two equivalent O(3)Cr3Fe2 trigonal bipyramids,  an edgeedge with one O(2)Cr2Fe2 tetrahedra, and edges with five equivalent O(3)Cr3Fe2 trigonal bipyramids.
FeCr2O4 crystallizes in the orthorhombic Cmcm space group. Cr(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of edge and corner-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles range from 0-56°. The Cr(1)-O(2) bond length is 1.99 Å. Both Cr(1)-O(1) bond lengths are 2.09 Å. There are two shorter (2.02 Å) and one longer (2.05 Å) Cr(1)-O(3) bond length. Fe(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(3) atoms. Both Fe(1)-O(2) bond lengths are 2.09 Å. All Fe(1)-O(3) bond lengths are 2.31 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a square co-planar geometry to four equivalent Cr(1) atoms. In the second O site, O(2) is bonded to two equivalent Cr(1) and two equivalent Fe(1) atoms to form OCr2Fe2 tetrahedra that share corners with two equivalent O(2)Cr2Fe2 tetrahedra, corners with ten equivalent O(3)Cr3Fe2 trigonal bipyramids, and edges with two equivalent O(3)Cr3Fe2 trigonal bipyramids. In the third O site, O(3) is bonded to three equivalent Cr(1) and two equivalent Fe(1) atoms to form distorted OCr3Fe2 trigonal bipyramids that share corners with five equivalent O(2)Cr2Fe2 tetrahedra, corners with two equivalent O(3)Cr3Fe2 trigonal bipyramids,  an edgeedge with one O(2)Cr2Fe2 tetrahedra, and edges with five equivalent O(3)Cr3Fe2 trigonal bipyramids.