In the field of switching conversion, it is considered that only the power of the converter is determining its size, weight and cost. But the power of the converter does not fully determine its parameters. The article shows that in a switching converter it is possible to allocate a virtual or real conversion unit than transmit energy through the magnetic field of inductor, and that the power of conversion unit can be less than or equal to the power of the converter. Therefor the difference between power of the converter and conversion power is existed. The article defines the conversion power for the most popular switching converters used in computer systems. Using known formulas, a check of the conversion power calculation for Buck, Boost and Buck-Boost converters in which the inductors operate in the same modes was performed. It shows the correctness of the theoretical assumptions. The introduction of the terms “Conversion Power” and “Conversion Unit” into the theory of switching conversion allows for a deeper understanding of the processes of switching energy conversion and the creation of new converter circuits for computer systems with better technical characteristics.