This paper describes the usage of MADYMO simulations in improving frontal crash sensor calibration. MADYMO simulations were conducted in the frontal impact program to improve the sensor calibration. In developing the advanced frontal impact restraint system using dual stage inflator, sensor calibration is very important. Late firing of the first stage inflator and large time delay between first and second stage time-to-fires increased occupant injuries. In the early version of sensor calibration, the initially given TTF’s were not satisfied in some test speed conditions due to late first stage TTF and large time delay. Therefore, in order to determine the correct required TTF’s, MADYMO simulations were used. First, the dual stage inflator was modeled as having two stages, which are primary and secondary stages. Then, MADYMO simulations were conducted by giving time delay between first and second stages of inflator model. Through simulations, the required TTF’s were determined, which produced the injury values meeting the customer targets, and it was found that the relatively large time delay could be used in the low speeds. With the new required TTF’s and the relatively large time delay in low speeds, sensor calibration was repeated. The recalibration was found to satisfy the required TTF’s from the MADYMO simulations. A sled test was conducted in the worstcase condition and the injury results met the regulation limits.