A large data set obtained for melt blowing using a single hole die has been used to develop empirical models which express final average fiber diameter as a function of dimensionless independent variables. The resulting empirical models or equations have been compared to multihole melt-blowing die data. The conclusion of this investigation is that appropriate first-order variables have been identified and the dependence of average final fiber diameter on the independent variables has been established. The resulting model should prove very useful for use in melt-blowing process control and in the design of melt-blowing equipment for polypropylene with an MFR between 500 and 900.