A method for controlling a hybrid powertrain system based upon determined inertial effects for a continuously variable operating range state includes monitoring an operator torque request and a rotational speed of the output member (64), determining an inertial effect on an input speed of the input member (12) for a continuously variable operating range state, and controlling motor torque outputs from the electric machines (56,72) to meet the operator torque request based upon the inertial effect on the input speed of the input member (12).