It is shown in this paper that exact expressions may be derived for the absorption factor for the intensity of Bragg reflection by a small euhedral crystal completely bathed in a parallel x‐ray beam. The expression is a sum of terms evaluated for subdivisions of the crystal determined according to discontinuities in boundary conditions imposed by the distribution of edges between the plane faces of the crystal. For a prismatic crystal of constant cross section, general expressions are derived for five general types of subdivisions in terms of the linear absorption coefficient and certain linear dimensions. Other expressions are also given for other types of subdivisions which arise in certain cases. The application of the method, including corrections for secondary extinction, is illustrated by calculations on tetragonal barium titanate.