It is well known that the extraneous Kα2 line complicates the interpretation of X-ray diffraction spectra. Experience has shown that the arms and weights calculated by Ladell's method [Laddell, Parrish & Taylor (1959). Acta Cryst. 12, 561–567] have to be determined for each user's X-ray diffractometer, rather than using the published coefficients, for an accurate Kα2 elimination. When different materials are analyzed, the signal/noise ratio can be optimized by choosing a suitable target material. Kα2 correction coefficients have been calculated for Cu, Co and Cr radiations using a fast Fourier calculation method.