A system for determining stiffness of an elevator system tension member includes a landing floor indicator to transmit a landing floor signal of an elevator car to a stiffness estimator, and a car position encoder to transmit a car position signal of the elevator car in a hoistway to the stiffness estimator. A machine position encoder transmits a machine position signal to the stiffness estimator. The tension member is operably connected to the machine to move the elevator car along the hoistway. A load weight sensor is located at the elevator car to transmit a load weight signal of the elevator car to the stiffness estimator. The stiffness estimator utilizes at least the landing floor signal, the car position signal, the machine position signal and the load weight signal to calculate an estimated stiffness of the tension member.