The references concerning the strength analysis of gears include a few methods of calculating the value of the face load factor (KHβ). In the paper, discussed are the C2 ISO method [1, 2, 3] and a method presented in [4, 5]. The two methods differ mainly in the way the bending and torsional deformations in the shafts and gears are calculated. On the example of the calculations of the first stage in a two-stage helical gear presented schematically in Fig.1, the influence of the these two different approaches on the value of the safety factors for pitting (SH) and tooth breakage (SF) has been analysed. The influence of four accuracy classes used in the manufacture of gearing (5, 6, 7 and 8) on the value of the safety factors SH and SF has also been evaluated.