Recreating the geometry of non-standard gears as part of reverse engineering is quite a challenge. Typically, when the modulus is standardized, during one of the steps of the gear inspection, which is the determination of the modulus, the measurement result is rounded to the nearest value from a series of standard nominal values. From that moment on, all other geometrical parameters of the gear are determined in relation to the already selected module. The situation is more complicated when the gear has a non-normalized and non-round module, e.g. m = 4.98. In this work, the authors determine an equation that allows for the determination of alternative geometrical parameters for a given gear, maintaining its complete identity. For example, a spur gear with straight teeth and parameters m = 4.98, y = 0.795, x = +0.0695, c * = 0.383 and α = 26.325 ° was used, which was replaced with a completely identical gear with the parameters m = 5.00, y = 0.793, x = +0.0325, c * = 0.380 and α = 26.784 ° due to the equation of the identity of the gears determined in the study.