Abstract The cold compaction in a tool of ferrous (ASC 100.29) and alloyed Fe-Mo (Astaloy 85 Mo) powders and the mixtures based on these powders with an addition of 3 wt. % of copper and 0.7 wt. % of graphite was quantified using four different compaction equations. A linear form of the dependence of porosity on pressing pressure enables to compare the exactness of used compaction equations. The analysis of correlations between the experimentally determined porosity and calculated porosity showed that the best results were achieved in the case of the compaction equation given by Parilak et al [10, 11]. This equation enables to determine: the total work “Xn”, which is necessary for achieving “full-dense” compact (P->0 at p->?) by rearrangement of particles and by their plastic deformation; the work “X1”, which represents the part of the work for densification by particles rearrangement without plastic deformation; the minimal compaction pressure “p1”, necessary for achieving a sufficiently strength green compact. The results showed that the pressure p1 is controlled mainly by morphology of powder particles, while the values of Xn and X1 depend on plastic properties of metal powder.