Theoretical work has not yet produced a full description of the x-ray diffraction line broadening due to the instrumental conditions in the absence of spectral broadening. Therefore in this paper an experimental approach was chosen. The line profile due to the instrumental conditions was obtained from the measured line profile of a standard specimen by eliminating the spectral broadening, applying a model for the wavelength distribution. Under common experimental conditions, it was found that for 2thetaÃœ050 the spectral broadening is dominant in the line profile, and that for the larger 2theta values and for small values of the harmonic number the Fourier coefficients corresponding to the broadening caused by the instrumental conditions may be assumed to be independent of 2theta. Therefore, if one is obliged to use in size-strain analysis a standard specimen that diffracts in a 2theta range different from that of the line profile to be investigated, corrections for the difference in broadening, due to the instrumental conditions, between the profiles of approximate and ideal standard specimens are unnecessary. Hence only corrections for the difference in spectral broadening should be made. In addition a method is proposed to determine the ratio R=I₉₇₂(max)/I₉₇₁(max).