The steady‐state mobility‐lifetime products (&eegr;&mgr;&tgr;) and photoconductivity spectra ofa‐Si:H anda‐SiGe:H films with band gaps from 1.74 to 1.10 eV have been determined. The importance of obtaining the bulk &eegr;&mgr;&tgr; at an appropriate wavelength for films of differing compositions and absorption spectra is demonstrated. We show that &eegr;&mgr;&tgr; measured at a wavelength such that the absorption‐thickness product is unity (&agr;t=1) is proportional to the standard photoconductivity measured at one sun illumination for films having a wide range of band gaps and deposition conditions.