Gas compressibility factor (z-factor) is an important parameter widely used in petroleum and chemical engineering. Accurate and fast calculation of this parameter is of crucial need and challenges a large number of simulators used in engineering. In this app, we are presenting a better way for calculation of this parameter.This application uses a 2-10-10-1 neural network to calculate compressibility factor (z-factor) of natural hydrocarbon gases based on Standing-Katz and Katz charts.To learn more about this method, see the following paper:Kamyab, M., Sampaio Jr., J. H. B., Qanbari, F. & Eustes III, A. W., "Using artificial neural networks to estimate the Z-Factor for natural hydrocarbon gases", Journal of Petroleum Science and Engineering, 2010, 73, 248-257.