This paper presents the design, implementation and validation of a forward simulator for a battery electric bus, developed in MATLAB/Simulink. This simulator allows performing energy consumption analyses for different bus routes. In addition, a user can modify some parameters that affect the powertrain operation to understand their influence in the energy consumption of the bus. These analyses allow the electric bus manufacturers to adapt their powertrain designs and control strategies for different transit agencies with different routes and energy requirements.The simulator was validated using real data from a battery electric bus. The results showed a good correlation between the real and the simulated data. In particular, the absolute error between the real and the simulated State of Charge (SOC), which is one of the most important parameters for this kind of vehicles, was 3.24%.