In this work an extension of the well-known DC power flow method is presented. A normal DC power flow of the system is executed to determine voltage angles and a novel derivation of voltage amplitudes is devised. The latter is rigorously formulated and eight alternative ways to tackle it are proposed. Comparative studies between the proposed versions of the algorithm verify its effectiveness in producing an accurate estimate of the voltage profile, on average in the order of 10-3 pu close to the exact solution. The proposed algorithm features very favorable computational requirements of approximately a fifth of the time required for an exact solution. Its computational efficiency renders it a solid candidate for hard real-time applications required in the emerging smart grid.