Microwave multiport sensors have been shown to provide some unique capabilities to achieve real-time testing of products conveyed at high speed. In many applications, quantitative measurements of physical quantities such as moisture content, density, etc… are required, either to guarantee reliable production or to optimally control a fabrication/transformation process. In this paper, different ways of extracting such physical quantities from microwave measurements performed by multiport sensors are presented. Model approaches are used, based on polynomial expansions of the physical quantities to be measured as a function of the microwave amplitude and phase data. Calibration procedures have been investigated for both paper and wood material samples. Comparisons between in-situ, microwave and conventional, measurements are analysed.