A system and method for determining the vapor pressure of a process stream includes a hard analyzer configured to measure one or more dependent variables associated with a sample of the process stream, where a dependent variable is also a property of the sample such as vapor pressure; a sensor system comprising one or more sensors configured to capture one or more independent process variables associated with the process stream; an aggregation module for collecting and storing outputs from the hard analyzer and responses from the sensor system; and a modeling module capable of generating a vapor pressure model from the same. The system then applies the model to sensor responses for the process stream to generate vapor pressure values.