Spiral inductors are critical components of design in Radio Frequency (RF) and microwave circuits. The design of spiral inductors has a direct influence on the performance of these circuits. Since their design process is limited to a specific area, technology, and geometry parameters, it is considered to be one of the most difficult and time consuming tasks. In this work Particle Swarm Optimization (PSO) was used to find the optimum geometry parameters of spiral inductor that give an optimum quality factor (Q) value for a given specifications. The PSO was initialized with 20 particles and 50 iteration for optimizing the spiral inductor and 8 particles for the transformer. All of the particles have set of geometry parameters that can give the desired inductance with tolerance of 0.2 nH. This was done by initializing a large number of particles randomly, then choosing the desired number of them that satisfy the inductance tolerance condition. The inertia weigh was decrease dynamically from 0.9 to 0.4 to motivate the search from global to local one. The algorithm was implemented using MATLAB 2011a. For the first part of this work, an example of a spiral inductor of a specific technology and layout constraints has been used. The first step was to find its optimum Q value. The second one was to make a trade-off between maximizing Q and minimizing the spiral occupied area. The result shows about 21.7% improvement for Q for the first step of the example. For the second one, the Q was improved with almost the same percent and with an area lowered from (395.4)2 to (383)2 μm2. The accuracy of the calculated results was verified using Advanced Design System (ADS) simulator. In addition, spiral planar transformer was also considered as an extension to the spiral inductor, since it consists of two coupled spirals. Second part of the work was to minimize its insertion loss of the transformer using the same algorithm. The insertion loss has been lowered from 1.11 to 0.84 dB at 4.5 GHz.