In the literature, it is common practice to use well-known and particularly robust numerical methods, such as the finite difference method and the finite element method for calculating the temperature in electronic components or devices. To calculate the operating temperature of a spiral planar inductor, we will adopt a method that is simpler to implement and gives equally reliable results. This method is based on the design of the thermal circuit of the inductor. The design of the thermal circuit results from the decomposition of the inductor into volume elements Vi and the similarity between the thermal and electrical circuits. By applying the nodal method, each volume defines a thermal sub-circuit. The assembly forms a complicated global circuit. This circuit is simplified into a "π" thermal circuit.The "π" thermal circuit associated with the Fourier's law facilitates calculation of the temperatures in different areas of the inductor. The obtained results are good and are validated by the simulation of heat flux. This simulation is performed with FEMLAB software.