In this paper, an equivalent three port scalable Inductor model has been developed for symmetric octagonal spiral inductors. The scalable inductor model is able to achieve good match for two port with center-tap connected to ground, three port differential and three port single-ended structures. Adjustable parameters include the number of turns (N), inner diameter (D), width (W) and spacing (S) of inductors. The model is verified to match well with simulation and measurement results.