An attempt was made in this paper to determine the regression rate of a hybrid fuel by using combustion chamber pressure. In this method, the choked flow condition at the nozzle throat of the hybrid rocket was used to obtain the mass of fuel burnt and in turn the regression rate. The algorithm used here is better than those reported in the literature as the results obtained were compared with the results obtained using the weight loss method and was demonstrated to be in good agreement with the results obtained using the weight loss method using the same motor and the same fuel and oxidizer combination. In addition, the O/F ratio obtained was in good agreement with those obtained using the weight loss method. The combustion efficiencies obtained were in good agreement with the average values. © 2014 IAA. Published by Elsevier Ltd. All rights reserved.