A method of determining the moisture content of a module of tobacco material, the method comprising the steps of: (a) transmitting a plurality of microwaves substantially through a portion of the module, such that the microwaves are transmitted microwaves; (b) receiving the transmitted microwaves such that the microwaves are received microwaves; (c) determining a phase shift and an attenuation from the received microwaves; (d) repeating steps (a) to (c) for at least a portion of the material on the module, such that a plurality of phase shifts and a plurality of attenuations is obtained; (e) using at least one empirical factor selected from the group consisting of weight of the module, temperature of the module, shape of the module and type of the material to correct the plurality of attenuations, producing a plurality of corrected attenuations; (f) calculating a raw moisture content of the material from the corrected attenuations; (g) determining a density of the material from the phase shifts; and (h) calculating a final moisture content of the material from the density and from the raw moisture content.