A new software is presented which allows to calculate cyclone efficiency for a given geometry or to determine a geometry for a desired efficiency is presented. It has been established for cyclones with relatively low solids loading (<10 g/m(3)) and it applies for pressure drop between 10 and 10 000 Pa, for cut diameter between 0.2 and 20 mum, for volumetric flow rate from 10(-4) to 1000 m(3)/s and for cyclone diameter from 0.01 to 3 m. The calculations are realised with four models presented in the literature. Comparison between model predictions and published measurements, shows that models used in the software predict pretty well the experimental results, obtained in a large range of operating conditions. Moreover, a comparison of the results obtained with these four models permits to select the model the most adapted, depending on inlet flow rate, temperature and pressure used. (C) 2003 Elsevier B.V. All rights reserved.