The output voltage of spiral generators, which are used for high voltage pulse generation, is derived analytically from a coupled wave analysis that includes the switch impedance, loading of the output terminals, and the influence of the finite conductivity of the spiral‐wound conductors. It is demonstrated that the spiral generator behaves like a damped LC resonance element which is charged by a fraction of the switch current. Graphs of the output voltage as function of dimensionless parameters and scaling relationships for spiral generators are given.