An algorithm to find the bandwidth (∆F) and half wave retardation (Vtz) of the transverse phase modulator for several elect optic materials with X, Y AND Z-cuts, is cast where ∆F and Vtz are calculated by determining the propagation constant of anisotropic metal clad electro optic rectangular waveguide before (ᵝa) and after (ᵝy) applied voltage through parallel electrodes. The optimum design with broad ∆F, lower Vtz and smallest propagation losses is done. It is found that KNbO3 without rolating of axes (Z-cut) is the best material but, DaTiO5 with rolating of axes (Y-cut) gives smallest figure of merit (VR/∆F. The values of, ∆F, Vtz and Vr/∆F are increased with the operation wavelength (λ). The propagation constant approximately, is independent of the electrode material and silver gives smallest losses. Either Ex or Ey give similar numerical results with exchange the orientation cases. The effect of modular or length can be treated by change the applied voltage with the same reciprocal ratio without rotating of axes.