We present a new version of the BEST tool, namely BEST_CP, aimed at the estimation of the Charging Profiles (CP) of electric urban buses. Both the original BEST and the new version have been developed by ENEA, within the Electric System Research framework, since 2016. In the original version, BEST aimed at exploring the technical and economic feasibility to serve bus-lines by battery electric buses (BEB) instead of conventional ones (diesel and methane). In the current version, BEST_CP focuses on the estimation of the electric buses charging impacts on the electric grid, also representing a useful tool for recharge infrastructure sizing. Starting from data on the annual bus service scheduling, for each bus-line, the model selects the more convenient recharge solution among the three considered: only at depot, just on night-time (Arch. A); only at depot, both day and night-time (Arch. AB); both at depot, night-time, and terminus, daytime (Arch. B). A simulation of the recharge operations is performed hourly, considering six typical running days, in order to quantify the amount of required recharge power and its spatial and time distribution. The analysis is performed using GTFS data made available by the TPL companies for seasonal bus service, and climatological observations at the locations considered. A description of the new procedures for GTFS processing and subsequent fleet, batteries and charging stations sizing is provided, as well as for the estimate of the daily Charging Profiles at terminus and depot. Finally, the platform for a user-friendly application of BEST_CP is described along with the results obtained for the Rome case-study.