In this article, a novel approach based on differential transfer matrix method is proposed for fast analysis and optimization of wideband planar tapered directional couplers. In this method, both even and odd modes can be analyzed independently to obtain overall scattering matrix. The new method accelerates the optimization time considerably in planar structures. An 8.34 dB tapered coupler in the frequency band of 1–12 GHz is designed and optimized in the form of offset stripline structure. The experimental result shows good agreement with theory. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1795–1798, 2014