In the presented publication, an attempt to develop the theory of mixing by considering rotor-stator mixers from the standpoint of mechanical mixing devices was made. The results of the research on energy consumption are given in the form of analytically substituted expressions for determining power and pressure difference as well as a flow rate in a stage of rotor-stator mixer composed of a pair of the perforated rotor and stator elements with a gap between them, depending on the features of the design, dynamic characteristics of the rotor and flows. The interrelationships between power, pressure difference, and flow rate in the stages of rotor-stator mixers are established. This makes it possible to define the characteristics of mixers, carry out their calculations and reasonably accept the rational design and processing parameters. The peculiarities of the components in obtained equations are indicated. Partial cases of the equations for power consumption in stages of rotor-stator-mixers operated in pulse and impulse modes are considered. The invariant form of obtained equations would help to ease the scaling of rotor-stator mixers.