This paper describes modeling of on-chip Inductors and transformers for high frequency integrated circuit applications. The effects of the substrate losses, substrate capacitances, overlap capacitances between the turns of spiral and the cross-under layer, and the oxide capacitance between the spiral and the substrate are included in the analysis. This model will facilitate on-chip inductor and transformer design. Quality factor and scattering matrix for ward transmission coefficient are computed based on the proposed model.