In this paper a numerical method is reported for the evaluation of the lattice parameters of any crystal structure, without using standard samples. This method makes use of the higher-order Laue zone (HOLZ) lines present in the transmitted disk of convergent-beam electron diffraction patterns, observed under kinematical conditions. The lattice parameters are evaluated by performing the best fit of the measured and the calculated distances of the HOLZ lines from the centre of the transmitted convergent-beam diffraction disk. This method has been tested by determining the lattice parameter of a simple cubic crystal in comparison with the method based on the configuration changes of the HOLZ lines as the cell parameters is changed. In addition, the crystallographic constants of a hexagonal structure are evaluated and the effects of extended lattice defects are shown.