A processing system for delivering a process gas to a reaction chamber using a recipe having a recipe flow rate is provided. The processing system includes a gas flow delivery system configured for delivering the process gas, wherein said gas flow delivery system controlled by a mass flow controller (MFC) to an orifice. The predicted flow rate is previously computed by pressurizing a gas. The predicted flow rate further being previously computed measuring a set of upstream pressure values of the gas via at least one sensor. The processing system also includes a programmed computing device configured for applying a calibration factor of a set of calibration factors to determine the predicted flow rate, the calibration factor being a ratio of an average of the set of upstream pressure values to an average of a set of golden upstream pressure values.